When this country's 1.9 million voters, 60 percent of them illiterate go to the polls today for the first time in 12 years, they will be confronted with a bewildering arrays of seven candidates running on eight tickets to succeed Hugo Banzer as president.

Only four of the candidates - Hernan Siles Zuazo. Victor Paz Estensoto, Rene Bernal Escalante and Juan Pereda Asbun - are expected to receive more than 5 percent of the vote. Pereda, is expected to win.

Pereda is a former Air Force general who was minister of the interior until last January when Banzer picked him to run as the more or less critical candidate of this country's seven-year-old military government.

The election has been stacked in Pereda's favor ever since. The government television station has covered his every speech while ignoring those of the other candidates. The government has taken advertisements in the newspapers touting its accomplishments while Pereda has had all the money he needs for other ads saying that he will continue the government's programs.

Most importantly, Pereda had a three-month jump on his chief rivals, Siles Zuazo and Paz Estenssoro. They were in exile and their parties banned until a hunger strike earlier this year forced government to allow them back.

While two teams of international observers, one sent by the Organization of American States and a second, led by Lord Erik Avebury of Great Britain, have arrived to monitor the elction, it is still widely believed that ballot-stuffing and rigged counting, long a staples of Bolivian political life, will occur if Pereda does not win on the basis of legitimate returns.

"It's all been fixed up, old boy," said a British businessman who has lived in La Paz for 10 years. It is a view shared by almost everyone, including Bolivians of all parties and foreign diplomatic observers.

Siles, who heads a center-left coalition that includes the pro-Moscow Communist Party and who is considered the only candidate within striking distance of Pereda, has said he would rather lose the election than resort to civil war afterwards - even if it becomes obvious that the election has been stolen.

Yet Siles, who served as Paz Estensoro's vice president from 1952 to 1956 in a government that came to power after it defeated the army in an insurrection, has said he cannot "guarantee political stability" if there are massive and obvious irregularities. Siles had a term as president from 1956 to 1960.

The Carter administration, which many Bolivians say pressured Banzer into calling the elections - contention firmly denied by U.S. diplomats here and by Banzer - has indicated that it approves the return to an elected government.

It is understood that U.S. Ambassador Paul H. Boeker has stopped signing new aid requests until after a new president is installed next month, a sign that the United States wants the election to be reasonably honest and expects the military to allow whoever is elected to take office.

The Pereda campaign has been based largely on the theme of peace, prosperity and stability - the three major accomplishments of the Banzer government which has also been characterized by corruption, mal administration and forceful suppression of opponents, according to diplomatic observers.

Because of high prices for tin, oil and natural gas - Bolivia's major exports - ws well as over $1 billion in foreign development loans. Banzer has presided over a country that has been growing at a 6 percent annual rate for several years.

Although Bolivia is still the Western Hemisphere's second poorest country, after Haiti, and despite the fact that many Indians here still remain outside the market economy, there have been improvements, in some cases dramatic, since Banzer overthrew another general in 1971 and installed himself as president.

The current government has also provided political stability, a considerable achievement in a country that has had about 180 coups and revolutions since it gained its independence 153 years ago. As recently as eight years ago, on Oct. 3, 1970, Bolivia had five presidents in a single day.

Pereda clearly has substantial support as heir apparent to the generally popular Banzer. Yet he will have to win by about 10 percent to overcome the general assumption here that there is a built-in "fraud factor" of 5 to 8 percent for any candidate supported by a government in power.

The six other candidates have based their campaigns largely on appeals to past accomplishments, anti-military sentiment and, in some cases, more radical economic policies.

It is generally believed that if Paz and Siles had been able to unite, one of them might have been able to overcome Pereda. As it is, Siles has waged an aggressive and increasingly effective campaign, according to most observers.

If none of the candidates wins a majority of the votes, the new president will be chosen by a parliament that will also be elected today.