The invention discloses a breeding method of a new thin-shell crassostrea hongkongensis variety. Crassostrea hongkongensis are different in shell thickness due to different breeding regions and are even of polymorphic biological characteristics of shell thickness in the same breeding regions, and according to the principle of negative correlation of the shell thickness and the dressing percentage, quantitative and economic synergic selection is realized by technical means of primary selection and secondary selection of shell thickness, self-breeding of population, oriental pure-breeding and the like in different breeding regions, and the new thin-shell crassostrea hongkongensis variety which is high in production and quality and stably genetic is obtained. Dressing percentage of 13-17% in conventional bred oysters is improved to 22-25%, and is improved by 30-90%, and firm practice foundation is created for improving yield of the breeding industry of the crassostrea hongkongensis. The breeding method has the advantages of simplicity and convenience in operation, high practicality, proneness to popularization and the like.