The invention provides a method for cultivating a new, convex-shell and thin-shell strain of Ostrea rivularis Gould in the north. The method comprises the steps: collecting parent oysters of Crassostrea gigas and northern Ostrea rivularis Gould firstly, performing synchronous maturity promoting cultivation, when gonads of the parent oysters of Crassostrea gigas and northern Ostrea rivularis Gouldare mature synchronously, performing acquisition of mature eggs of Ostrea rivularis Gould and sperms of Crassostrea gigas, performing hybridization and fertilization so as to obtain a hybrid filial generation of the parent oysters, cultivating the filial generation after the hybrid group is obtained, adopting a microsatellite molecular marker technique to confirm that the first hybrid filial generation is the first filial generation of hybridization of Crassostrea gigas and northern Ostrea rivularis Gould, then adopting a truncated selection method to cultivate the first filial generation for1-2 years in a northern breeding sea area, and performing continuous one-to-one selfing on the hybrid strain so as to obtain the new, convex-shell and thin-shell strain of Ostrea rivularis Gould. Theobtained new strain of Ostrea rivularis Gould has the advantages of large shell convexity, thin shells, fast growth, high meat yield and the like.