Based on the samples collected by Chinese saury fishery fleet from the sea of the northwest Pacific Ocean from June to July and October to November in 2015, with the ratio of statolith maximum width (MW) to total length (TSL) as an indicator of statolith growth,the relationship between of statolith growth, sexual maturity and body size of Cololabis saira in the Northwest Pacific Ocean was analyzed by the analysis of variance. The results showed that statolith of Cololabis saira was flat and oval, its focus was on the backend and it has an apparent rostrum which is longer than the antirostrum; In addition to Ⅳ stage, TSL and MW mean of female and male individual increased with increased sexual maturity level. TSL and MW mean increased obviously from Ⅳ to Ⅴ stages. There was not significant difference between their MW/TSL (P>0.05) for the female and male individuals at four sexual maturity stages, the statoliths of Cololabis saira hardly changed their shape after the sexual maturity stage Ⅰ. As fork length increased, TSL and MW mean of female and male individuals increasd gradually, TSL and MW means had significant difference between fork length groups (P<0.05). There was not significant difference between their MW/TSL (P>0.05) for the female and male individuals in different fork length groups, and growth of MW to TSL (MW/TSL) was not obvious. With the fork length increasing, Cololabis saira statolith grew uniformly from stage Ⅱ of sexual maturity.