The invention provides a seed production method of a black-shell pacific oyster new strain. The seed production method comprises the following steps: firstly, two preliminarily screened shells are black with black mantles and high rate of flesh in body, and a group with a regular shell shape is taken as a core population; pacific oyster individuals with black shells, high rate of flesh in body and black mantles are selected out as an optimal population by adopting a size selection method and carry out offspring cultivation according to a conventional shellfish breeding method as a reproductive population to obtain a black-shell new strain F1; through a family line breeding mode, the black shell character is further purified to form a second-generation breeding family line F2; and finally, through continuous purification of a plurality of generations, a new strain with stable characters is obtained. According to the seed production method, the black-shell pacific oyster new strain with stable genetic character can be obtained, and the mantle melanin and the rate of flesh in body of obtained oysters in the new strain are both greatly increased.