The invention discloses a breeding method of common mudflat shellfish by convergent cross. The method comprises the steps: mudflat shellfish parents from more than four different geographic populations are collected; the shellfish parents of different geographic populations are carried out eco-maturing; then dual reciprocal cross is carried between two geographic populations; a first filial generation of dual reciprocal cross combination is bred up by a three-stage method; then the convergent cross of the first filial generation of dual reciprocal cross is carried out so as to obtain a first filial generation of convergent cross; and the above steps are repeated on the basis thereof till the filial generation of convergent cross accumulates the good genes of all the geographic populations. The method overcomes the geographic isolation and the biological differences of sexual maturity and breeding among different geographic populations. Compared with the existing mudflat shellfish varieties, the shellfish integrates the good genes from more than four different geographic populations; the heterozygosity is improved greatly, thus causing the converged half-bred individual to present characteristics of fast growing and high stress resistance.