The deal to buy the Su-35 fighters and Lada-class submarines was signed before the recent visit by President Xi Jinping to Moscow, the Chinese newspaper People’s Daily cited state television on Monday.
According to the report, it is the first time in a decade that Beijing purchases “large military technological equipment” from Moscow.
China’s military expansion comes amid its dispute with Japan over a chain of uninhabited islands claimed by both countries in the East China Sea.
Two of the submarines will reportedly be built in Russia, with the other two to be built in China. The value for the agreement, however, was not mentioned in the report.
Moscow and Beijing are also expected to work together in the field of military technology, which includes building S-400 long-range anti-aircraft missiles, 117S large thrust engines, IL-476 large transport aircraft and IL-78 aerial tankers, according to the report.
However, China's Defense Ministry has not commented on the report yet.
The Chinese president paid a three-day visit to Moscow from Friday to Sunday. He held talks with his Russian counterpart Vladimir Putin during his first foreign trip since becoming president earlier in March.
The two sides reportedly signed about 30 deals in the energy sector and other areas during Xi’s stay.
The Chinese president also met with Russian Defense Minister Sergei Shoigu, becoming the first foreign head of state to visit the Russian armed forces' control center.