Once considered part of a "front line" bracing for a possible attack from the Soviet Union, the northeastern Chinese city of Harbin now appears to face potential benefits from increased Sino-Soviet trade. No one talks much any more about the deep air-raid shelters built under Harbin following border clashes with the Soviets 16 years ago. Some sections of the underground labyrinth of tunnels and shelters seem to be falling into disrepair.

According to a recent issue of the official China Daily newspaper, the port of Heihe, located north of here on the Soviet border, is to be "drastically expanded" to accommodate expanded trade with the Soviet Union and Eastern Europe. About six weeks ago, a Chinese provincial delegation met in Blagovenshchensk, on the Soviet side of the Heilong River opposite Heihe, and agreed to terms for opening trade between the two river ports for the first time in two decades.

Harbin is the capital of Heilongjiang, a province bordering the Soviet Union. By most logical standards, it would gain greatly from the expanded Sino-Soviet trade called for in a five-year, $14 billion agreement signed in Moscow last month.

While the old hostility toward the Soviet Union appears to have subsided, it does not seem to have been replaced by any great enthusiasm for doing business with the Soviets. If interviews with officials here are any indication, Harbin and its surrounding province would now prefer to see western nations rather than the Soviets bring in new technology, trade and investment.

American technology, in particular, appears to be highly prized here; Soviet technology is considered primitive. Although few American firms have done much business in Harbin, the U.S. Westinghouse Corp., which helped build a large electrical power generator here, seems to have impressed Chinese officials with its technological capabilities.

The Soviets were deeply entrenched here in the 1950s. If they now want to modernize some of the factories that they helped design and build here in those years, Chinese officials say they must compete for contracts against the Americans, West Europeans and Japanese.

An industrial center of nearly 3 million people, Harbin is the closest major Chinese city to the Soviet border.

The largest former Russian settlement outside the Soviet Union, it was once very much a Russian city. Developed as a railway center by the late 19th century czars, it has grown from a fishing village to a city of more than 100,000 European residents.

Harbin's cobblestone streets and yellow-painted buildings with white trim evoke the city's Russian past. Only a handful of aging White Russian residents remain.

A war memorial to Soviet troops who fought the Japanese here toward the end of World War II reminds one of a second wave of Russian influence. After the war, the Soviets helped design and build 22 sizable factories. The new agreement signed in Moscow calls for Soviet cooperation in modernizing factories built in China with Soviet aid in the 1950s. Only three of those factories are reported to be located in Harbin.

A single Soviet technician has been working at the huge Harbin linen textile factory here under a short-term contract to help install and monitor four Soviet-built looms. Persons who have spoken with the technician say that he feels the Chinese have ignored most of his best advice.

Zhu Yaosheng, director of the Harbin City Economic Committee, said that the Chinese want to compare terms offered by various companies before deciding who should do the major modernization work at the linen factory. He said that Japanese and West German firms have shown an interest.

In an interview, Zhu said that he hopes American companies will send more trade delegations to Harbin.

Zhang Bin, deputy director of the Heilongjiang provincial foreign affairs office, said that the Soviets offer the advantage of being familiar with much of the equipment in the factories in question.

Because trade with the Soviets is based on barter, or swapping goods, it would not cost the Chinese any of their valuable foreign exchange to get Soviet assistance, he said. However, Zhang said that the Soviets are "not so advanced in terms of technology" and that barter trade can be cumbersome.

Heilongjiang, he said, needs timber, glass, steel, chemicals and building materials from the Soviets, but the Soviets have a great need for these items as well. Chinese exports to the Soviet Union consist mostly of light industrial products and foods, such as grains, corn and soybeans.

The province's transportation network is limited in its ability to cope with greatly expanded Sino-Soviet trade. According to a report published recently in the Far Eastern Economic Review from the border town of Heihe, the Soviet Army dismantled that railway line when it withdrew from Manchuria following the victory over Japan in World War II.

What is certain, though, is that the atmospherics of the relationship with the Soviets have improved greatly. One small sign of a thaw: Chinese trained by the Soviets no longer have anything to fear from demonstrating their Russian language abilities.

"They called me a spy during the cultural revolution, because I had studied in the Soviet Union," said Zheng Han Kang, senior engineer at a Harbin measuring tool factory. He is fluent in Russian, thanks to his Soviet training. "Now I can use the Russian language openly again," he said.

People seem to be willing to forget that the Soviet Army stripped the region of much of its factory machinery when the Soviet troops withdrew after World War II.

Asked how people felt about what is known in the West as the Soviet "rape of Manchuria" at the end of the war, a Chinese provincial official said, "We have mixed feelings. We're thankful for their efforts to fight the Japanese but resent their taking things from the Chinese people."

The official also indicated that the Chinese still remember that none of the territory taken by the czarist Russians from China under what are considered here to have been "unequal treaties" has been returned to China by the Soviets.

Another Harbin official was willing to forget the "rape of Manchuria," consigning it to history -- the kind that need not be mentioned in the history books.

"It is part of history," he said, adding, with a curious twist of logic, "so it will not be mentioned in the history books."