When Pavel Sukhoi developed the Su-27 fighter, he did not consider exporting it in the future.
China’s access to the Su-27 was benefited from the warming Sino-Soviet relations in 1989. During Soviet President Gorbachev’s visit to China in May 1989, he proposed to reopen arms and equipment trade, between China and the Soviet Union.
The Soviet Union tried to sell MiG-29s to China, because China had a long history of using and improving MiGs; however, after witnessing firsthand the new Soviet fighters, the Chinese were most interested in the Su-27. The large combat radius and tactical performance of the Su-27 fighter was much higher than the MiG-29, won the love of the Chinese.

The Su-27 adopted an advanced Soviet Union’s first operational fly-by-wire control system. It had more powerful engines and a longer lifespan. This was a combat platform with a lot of potential for improvement and future upgrades, and would be the next generation of Chinese fighter design. Chinese designers could learn a lot from the Su-27.
China has carefully calculated the purpose of purchasing the Su-27 fighter, in order to modernize its air force and in the long-term plan. Their plan was to replace the country’s outdated J-7s; at the same time, to build a modern aviation industry, from copying and improving fighters designed by the Soviet Union.
Chinese military experts believe that the fighter designed by Sukhoi was superior to the MiG fighter. The Su-27 had an aerodynamic form and a large fuselage, more suitable for refinement and upgrade. The Soviet Union may not want to export Su-27 fighters, but economic difficulties at that time forced them to agree to export the Su-27 to China.
The Chinese side emphasized the “close” relationship that the two countries had in the past, and at the same time hoped that China and the Soviet Union could improve their relationship after a long “indifference”. But in general, economic benefits were the real goal.
After the conclusion of the 1990 winter negotiations, China and the Soviet Union signed an agreement with China to purchase 24 Su-27SK and Su-27UBK aircraft. Although the Soviet Union collapsed later, Russian President Yeltsin, still complying with the agreement. The first batch of Su-27 fighters was delivered to China on June 27, 1992.
But that was not enough for the Chinese. China clearly saw the serious economic difficulties the Russians faced in the 1990s, and prompted Russia to transfer production technology of the Su-27, including the complete production line, to China. Agreement was reached in 1995; China then began to produce the Su-27 under license.