Many factors affecting on growth of clam have been studied, however, aquiculture density as a factor on clam growth has not been reported frequently. This study intends to demonstrate the correlations among farmi ng density, growth and the concentration of sulfide in the sediment. A growth e xperiment was carried out at Xinzhong Sea Products Development Co., Ltd., NanTong. Healthy juvenile clam (150-160 μm shell height) were collected from induced breeding on 28th July 2005. The results indicated that (1) the concentration of sulfide in the sediment was increased with aquiculture density . And Instantaneous Growth Rate (IGR) of juvenile clam showed significant nega tive correlation with concentration of sulfide in the sediment. IGR= 8.22×10^-2-0.484C_s(P<0.05, n=30).(2) In the five density groups, 200,400,600,800,1 000 ind·cm_-2, the highest instantaneous growth rate(7 μm·day_-1) was presented in the lowest density group B, furthermore, with the increase of aquiculture density, instantaneous growth rate was decreased gradually, meanwhile, mortality accrued rapidly. (3) Density as a factor in aquiculture affects on growth through two different ways：for one thing, the competition for space and food between clam individuals, for another the effect on environment (for instance the concentration of sulfide and bacteria in sediment) reacts on growth of juvenile clam.