The clams from different coastal areas are compared according to the feature of figure on the shell. The results show that there are no obvious stripes on the shell of the clams from Guangxi Coast. The clams collected from Liaoning, Shandong, Zhejiang and Jiangsu coasts are classified into two groups in stripe color and pattern, and the stripes of the calms from Shandong are similar to that from Zhejiang. The microscopic anatomy of mantle of Meretrix meretrix is described through histological technique. The typical structure of the mantle of bivalve consisting of a middle zone and a marginal zone is observed. There are three protuberances in the marginal zone. The mantle is composed of inner epithelium, outer epithelium, connective tissue and muscular fiber. There are pigment cells in the epithelium.