Delegates to Poland's extraordinary Communist Party congress today started electing a new leadership by secret ballot for the first time in the Soviet Bloc.

A final list of 384 candidates for 270 members and deputy members of the decision-making Central Committee was drawn up on the third day of the congress following lengthy haggling among groups of delegates. In addition, another 235 candidates are fighting for 160 seats on the party's control and auditing commissions.

Under usual communist procedures, candidates for such posts are selected beforehand by the leadership and then approved unanimously by open show of hands at the congress.

The first round of voting for the major party committees was completed late tonight, but officials said the results would not be announced until Friday morning following scrutiny of returns by officials. Only candidates who win at least 50 percent of the vote will be declared elected while the remainder will have to face a second, and possibly a third, ballot.

The first task of the new Central Committee will be to propose candidates for party leader, to be elected by the congress. The outgoing first secretary, Stanislaw Kania, is expected to face as many as half a dozen opponents representing both the reformist and hard-line factions in the party.

The most remarkable fact about the choice of candidates in the elections currently under way is that only 12 percent are members of the outgoing central authorities. Even assuming that most of them get relected, this means that the new Polish Central Committee will be made up overwhelmingly of new faces.

After scarcely 10 months of practice. Poland's Communist Party -- in common with the rest of the nation -- is still learning how to make democratic procedures work.That is one reason why procedural arguments at this congress have been heated and have even, in the view of some participants, distracted attention from the primary purpose of freeing Poland from its political and economic crisis.

Asked about the lengthy floor fights, one of the delegates, Dominik Horodynski, who is editor in chief of the prestigious literary magazine Kultura, said he believed they were inevitable in Poland's present situation. "These fights could go on for hours," he said. "Nobody is likely to attempt to curb them. It is a result of our hunger for full democracy and having our own say in everything."

At the start of the congress, Kania told delegates that when it came to elections, no better system had yet been devised than the secret ballot.

The translation into English may have changed the sense of what he wanted to say. But, to a foreign ear, the way he talked about secret voting had a kind of innocent, even touching quality to it, as though he had just discovered the wheel and wanted to tell his friends what a wonderful thing it was.

New voting procedures would have been educative for the representatives of the "fraternal" communist countries at the congress, had they been allowed to witness them. In fact, after delivering their speeches of greeting to open sessions of the congress, they were dispatched to address meetings of factory workers before returning home.

Of course Kania, like the product of any power apparatus, is hardly a political innocent. One-man, one-vote may be a democratic mechanism but he knows how to use it to his own advantage.

Not all votes are held in secret -- and this gives the leadership a possibility of influencing the results. Simple procedural questions are decided by open show of hands during which a delegate is less likely to court attention by going against the leadership's wishes.

At a Central Committee meeting last month, Kania was able to isolate his hard-line challengers by calling for an open vote on whether or not to proceed with a motion of confidence in individual Politburo members. Ironically, the same trick failed to work a second time at the congress when the delegates turned down a proposal to immediately reelect him first secretary. Kania's vote-winning magic was broken.

The Polish party congress is certainly much freer than previous such meetings, but it would be wrong to depict it as an exercise in Athenian-type democracy. As at an American political convention, many forces are at work behind the scenes. Votes are traded in return for jobs and the reputations of some of the candidates are blackened by slurs.

The key to the horse-trading is held by the leaders of the provincial party caucuses at the congresses and particularly those representing the big cities: Warsaw, Katowice, Krakow, and Gdansk. It was they who haggled among each other over who would be nominated as candidates for leadership posts.

Some of the voting, however, has cut across provincial lines and there is no guarantee that the delegates will respect the choice of their particular caucus when it comes to the final ballot.

Following the nominations, a question time was held for the candidates. According to congress sources, the most pointed questions concerned the candidates' records during the 1970s. Several of the present Politburo members, including Kania, held high positions under Edward Gierek's now-discredited leadership. k

The 1,955 delegates (whittled down by illness from 1,964 elected) are sequestered behind elaborate security protections. Police supervision extends from the Stalinist-Gothic Palace of Culture, where the congress is being held, to their hotel rooms. To prevent any incidents at the meeting, the delegates are required to report their every movements.

Contacts with foreign journalists are also controlled. This has sharply restricted the number of leaks from the closed sessions of the congress. Most information is channeled through the official spokesman, Wislaw Bek, who is also editor of the party newspaper and a candidate for the Central Committee.

Ordinary Poles are reacting to the congress with a range of responses, from considerable interest to indifference. Usually, Communist Party congresses are accompanied by exhortatory fanfare in the media, which is controlled, and a sudden stocking up of supermarkets and department stores with an abundance of goods.

This time the propaganda has been muted, and the shops are as empty as ever. For form's sake, a few posters and flags have been put out and the Palace of Culture is decorated with a massive red map of Poland emblazoned with the party's initials. The Solidarity union has responded with pamphlets proclaiming an airline strike of indefinite length starting a week from Friday.

A public opinion poll, itself a novelty in a communist country, showed that only one-third of those questioned believed that the congress would result in "changes for the better" while half expressed the view that nothing would change.

Random conversations with passers-by on one of Warsaw's major shopping streets reinforced this view. Asked who they would like to vote for as party leader, the respondents mentioned Kania or two leading reformers, Tadeusz Fiszbach and Mieczyslaw Rakowski. There was no noticeable support for hard-line candidates.

A minor controversy broke out over an allegation published in a Solidarity bulletin saying that delegates to the congress were to receive an extra ration of 5.5 pounds of best quality meat and 2.5 pounds of sausage. The report so incensed one delegate that he demanded a special congress resolution condemning it as slander.

His suggestion was approved by acclamation -- without a secret ballot.