Abstract: Statolith is an important hard tissue in cephalopod,which may better reflect the ecological information.Illex argentinus located in the southwest Atlantic is one of important economic cephalopods in the world,which is also one of the important fishing targets for Chinese squid jigging fleets.Mastering the basic biological characteristics and revealing the life cycle process of Illex argentinus is the base for scientificalty developing and exploiting Illex argentinus. According to the samples of Illex argentinus totaled 560 in number collected by Chinese squid jigging vessels from 2007 to 2008 in Southwest Atlantic Ocean,the total statolith length(TSL),maximum width(MW),dorsal dome length(DDL),ventral dorsal dome length(DLL),lateral dome length(LDL),rostrum lateral dome length(RLL),rostrum width(RW),rostrum length(RL),wing length(WL)and wing width(WW)are considered as the indicator of dome growth,and the ratios of MW to TSL,RW to RL and WW to WL are considered as the indicator of changes in statolith shape.The dome growth and statolith shape changes effected by sex,gonad maturity and individual size are analyzed by the analysis of variance(ANOVA)and Least-significant difference(LSD).The results indicated that the changes TSL,MW,DLL,DDL,RLL,RL,WL and WW between different sexes were significant(P<0.05).For both female and male samples,the changes of TSL,MW,DLL,LDL,WL and WW between different gonad maturity and different mantle length ranges were also significant(P<0.05).However,the ratios of MW to TSL,RW to RL and WW to WL changes in different sexes,different gonad maturity and different mantle length ranges show no significant differences.The results indicated that the mantle length group(301-350 mm)may be the turning point of the growth of statolith.