Soviet First Deputy Premier Ivan Arkhipov left the capital today to tour China's south after four days of talks with Chinese leaders aimed at increasing trade and economic cooperation and easing tensions between the two communist neighbors.

Arkhipov, the highest ranking Soviet envoy to visit China since 1969, held three rounds of talks with his Chinese counterpart, Vice Premier Yao Yilin, and met with Premier Zhao Ziyang last night. The talks resulted in agreement on four new accords.

Before he left today, Arkhipov, who handles the Kremlin's economic affairs and headed the massive Soviet aid program here in the 1950s, met with "two old friends" -- Chen Yun, a Politburo standing committee member and expert on the Soviet economy, and Bo Yibo, executive vice chairman of the committee in charge of party rectification and a close friend of China's paramount leader, Deng Xiaoping.

Arkhipov had close contacts with Chen during the 1950s, when he served as chief adviser to Soviet experts in China and helped map out and implement China's first five-year plan.

Chen told the 77-year-old economics minister, "You are an old friend of ours. . . . We worked well together when we were drawing up and implementing China's first five-year plan in the 1950s," according to a spokesman for the Chinese Foreign Ministry.

"The Chinese government and people have not forgotten and will never forget the aid given them by the Soviet government and people in the past," the official New China News Agency quoted him as saying.

But Chen also reiterated China's position that "three major obstacles" had to be removed before relations between the two countries, which have been strained by a 20-year ideological and strategic quarrel, can be improved.

Peking insists that Moscow end support for Vietnam's occupation of Cambodia, withdraw from Afghanistan and reduce its forces on China's border.

"This does not mean that China and the Soviet Union . . . cannot improve and develop ties in other fields," Chen said.

The remarks underscored earlier predictions that there would be no major political breakthroughs during Arkhipov's visit.

But diplomats here have said that increasing contact through nonpolitical channels, a policy China has adopted in the past two years, will add to the overall momentum for eventual upgrading of political ties.

The two sides have agreed on the texts of three accords to increase economic, scientific and technological cooperation. They may be signed before Arkhipov leaves Saturday to return to Moscow.

Although neither side has released any details of the accords, they are expected to include Soviet assistance in upgrading and providing machinery for the factories and projects that were built with the help of Soviet technology and assistance in the 1950s.

The fourth accord is a five-year trade agreement to be signed by mid-1985. That agreement is likely to boost trade from the current $1 billion to between $5 billion and $6 billion by 1990, about the same level as current U.S.-China trade.

The Chinese have been eager to show the Soviets their domestic economic changes, which emphasize a market economy instead of the Soviet-style centralized planned economy. And the inclusion of a trip to the special economic zone of Shenzhen -- where the changes are said to have achieved great success -- represent a victory of sorts for the Chinese, diplomats said.

Arkhipov is scheduled to visit Canton, then Shenzhen across the border from Hong Kong, and then the city of Wuhan, where he will visit the steel mill he helped set up in the 1950s, according to Da Gong Bao, newspaper of the Chinese Communist Party in Hong Kong.