Argopecten irradians concentricus Say, introduced from America, has been extensively cultured in recent years in Beibu bay in Zhanjiang, but the research about its morphological growth is not found to have been reported, this makes the culture of Argopecten irradians concentricus Say lack of the guiding of relevant theory. The morphological growth of Mexican bay scallop(Argopecten irradians concentricus Say) in Zhanjiang Beibu bay sea area was investigated in this paper by using model fitting procedure under such conditions as seawater temperature ranging from 18.2℃ to 30.8℃, salinity ranging from 27.8 to 30.4, limpidity ranging from 1.5m to 5.7m, water depth at 9.7m, average planktonic plant cell abundance at 4.3104cellL-1 and the autumu-winter-spring culture mode in which the time span of the investigation was exactly equivalent to one culture cycle of Mexican bay scallop. Results showed that the growth of morphological traits of Mexican bay scallop conformed to Logistic model, with squared multiple correlation coefficient R2 all exceeding 0.98 (P<0.001) and root mean square error (RMSE) averaging out at 0.897. All Logistic models of varying morphological traits were statistically significant (ANOVA, P<0.001). Growth parameters contained in Logistic model, estimated by Levenberg-Marquardt iteration method, could be employed in establishing the growth equations of varying traits of interest. Growth limits and confidence intervals of varying morphological traits of Mexican bay scallop in Zhanjiang sea area were, shell length 53.8mm, shell height 54.6mm, shell breadth 27.1mm,hinge length 28.4mm, adductor length 26.1mm, adductor diameter 16.2mm, respectively; the fastest growth intervals and growth inflection points of varying morphological traits were, shell length 1.5-5.7 months and 3.6 months, shell height 1.4-5.9 months and 3.6 months, shell breadth 2-6.4 months and 4.2 months, hinge length 0.7-4.8 months and 2.8 months, adductor length 1.9-6.5 months and 4.2 months, adductor diameter 1.6-5.5 months and 3.5 months, respectively. Growth delay with shell width and adductor length took place. In terms of the absolute growth rate, there was this sequence, viz., shell length>shell height>shell breadth>adductor length>adductor diameter, the relative growth rate were different among traits of interest and gradually tended to 0. It was found in the study that delay of the growth of shell width and adductor length traits occurred, there existed significant difference in terms of morphological growth between varying geographic populations, the growth of morphological traits were controled by both temperature and growth phase. New viewpoints of opportune harvesting according to the growth of shell width and adductor length traits and of arranging the fast growth period into most favorable season so as to maxically harness growth potential were proposed. Results obtained can serve as theoretical guidelines for predictions of future changes in culture ecology, selection breeding and production of Mexican bay scallop.