Abstract: Based on the research of juvenile (9 months)growth and survival of three populations of Chlamys farreri from two different geographic areas in Dalian of China and Ishinomaki of Japan and their F1 hybrids derived from Chinese population (C)♀×Japanese population (J)♂and Japanese population (J)♀×Chinese population (C)♂, the study of the medium-term(11 , 13 , 16 , 18 months)growth and development of C .farreri was carried out .The four determined results indicated that there existed heterosis of varying degrees (5 %-50 %)for growth in two types of F1 hybrids and the offspring derived from J ♀×C ♂had a higher heterosis than the offspring derived from C ♀×J ♂;the uptrend among traits are live weight >shell length >shell height >shell width ; Japanese population slightly exceeds Chinese population ;and season influence on the daily increment and growth rate of each trait of C .farreri was highly significant and it is losing weight in a state of survival in winter (18 month).