MOSCOW, SEPT. 13 -- The most far-reaching economic reform plan to be embraced by the Soviet leadership since the 1917 Bolshevik revolution aims at transforming the world's first Communist country into a land of shopkeepers, small businessmen, private farmers and stockholders within two years.

The full text of the "500 Days" program endorsed by President Mikhail Gorbachev earlier this week includes proposals for the largest bankruptcy sale in world history and the denationalization of 80 percent of the Soviet economy by the end of the decade. A copy of the 452-page document was obtained today by The Washington Post.

In the view of many Soviet and Western analysts here, the plan marks the effective abandonment of Gorbachev's five-year attempt to "renew" communism under the slogan perestroika or "restructuring." The new program, which mentions the word socialism only in passing, is clearly aimed at introducing a Western-style mixed economy in the Soviet Union rather than at reforming communism. "Mankind has not succeeded in creating anything more efficient than a market economy," the authors declare.

At a press conference today, one of Gorbachev's top economic advisers, Nikolai Petrakov, scarcely objected when a journalist suggested that the Soviet Union was abandoning socialism altogether. "If it's the socialism that {former dictator Joseph} Stalin created, we certainly want to get rid of that socialism. We don't want to have anything to do with it. What we want is an efficient economy," he replied.

"Capitalism is coming to the Soviet Union," said Donald Marron, chairman of the Paine Webber financial services group and a member of a delegation of leading U.S. businessmen headed by Commerce Secretary Robert A. Mosbacher, at another news conference. Marron said he was impressed by moves to introduce stock exchanges in Moscow and Leningrad.

The "500 Day" plan, written by a group of economists appointed by Gorbachev and the Russian republic's president, Boris Yeltsin, has already been adopted by the Russian legislature and is likely to be discussed by the Soviet legislature next week. But there are still huge barriers to its effective implementation, notably the opposition of leading government officials and popular concern that it could lead to spiraling prices and large-scale unemployment.

In an attempt to cushion the shock of a rapid transition to a free market system, the authors of the plan have attempted to place the burden of sacrifice on the state rather than the individual. They propose soaking up the excess money supply, now estimated at more than 200 billion rubles or half the annual budget, by a huge sale of state assets over the next six months.

The plan envisages the privatization of 46,000 industrial enterprises and 760,000 trade enterprises. The only sectors of the economy that will remain directly in state hands are defense industries, military installations, long-distance communications, the railway system, the postal service and a unified power system.

Larger companies will be sold off as joint stock companies at open auctions, with up to 10 percent of the stock reserved for employees of the companies. But smaller firms and stores employing up to 10 people (seven people for food stores) will be sold directly to anyone willing to buy them.

The plan calls, for example, for the sale to the private sector of 68 percent of all food stores, accounting for 30 percent of total turnover and employing half a million people. It also envisages the sale of about 50,000 restaurants, accounting for 60 percent of total turnover, and the creation of more than 150,000 peasant farms as money-losing collective and state farms are forced to disband.

The authors of the plan maintain that the sale of state assets will soak up most of the so-called "hot rubles" now in circulation, money that would be spent instantly if anything worth buying ever appeared in the shops. They claim that the measure will restore balance to the economy, avoiding the danger of hyperinflation as soon as prices are freed.

At a news conference earlier this week, Prime Minister Nikolai Ryzhkov argued that the "500 Days" plan would lead to uncontrolled price rises and large-scale unemployment. Ryzhkov, who has drafted more cautious proposals for economic reform, has indicated that he will resign if he does not get the backing of the Soviet legislature.

Drafted by a committee headed by presidential adviser Stanislav Shatalin, the "500 Days" plan also envisages the liberalization of the Soviet Union's foreign trade activity. Foreign companies will be given the right to own 100 percent of the shares in Soviet companies and use their ruble profits within the country. The ruble will gradually be made convertible.

Secretary Mosbacher predicted tonight that the remaining obstacles to granting the Soviet Union most-favored nation trading status were likely to be removed within the next two months. He quoted two Kremlin officials as saying that the Supreme Soviet is likely to pass a liberal new emigration law "in the next four to eight weeks" that would allow the administration to recommend that Congress waive the Jackson-Vanik amendment restricting Soviet trade.

The Shatalin draft calls for the development of normal economic relations with all foreign countries, including South Africa, traditionally shunned by the Soviet Union. It also calls for a 75 percent cut in all forms of economic assistance except humanitarian aid to foreign countries, a move that is likely to have a devastating impact on client states such as Cuba, Ethiopia and Vietnam.

Petrakov, Gorbachev's top economics adviser, said supporters of the old "command administrative system" are practicing a "scorched-earth policy" in a desperate attempt to block economic reform. He blamed the collapse in the purchasing power of the ruble on government bureaucrats who hope that the lack of basic consumer items such as bread and cigarettes would lead to demands for the introduction of full-scale rationing.

Yeltsin supporters announced plans tonight to hold a huge demonstration in central Moscow Sunday to demand the resignation of the Ryzhkov government and adoption of the Shatalin plan. The organizers are hoping that at least 300,000 people will take part in the rally, which will be held under the slogan "The People Are Tired of Waiting. Resolute Changes Now."