According to the samples of neon flying squid (Ommastrephes bartramii)collected by Chinese squid jigging vessels during July to October in 2007 in the traditional fishing ground of northwest Pacific Ocean,the population structure,age and growth of O.bartramii are obtained from the statolith microstructure.The results indicated that the mantel length of female squid ranged from 200 to 395 mm with the age ranging from 123 to 256 d,and the mantel length of male squid is between 200 to 353 mm with age ranging from 127 to 274 d.In July and August the dominant age is from 151 d to 180 d,the ages of 181 to 210 d account for the most in September,and the age class of 211 to 240 d takes up the dominant part in October.The hatching dates of sampled squid were from December 2006 to June 2007,and the peak hatching dates are distributed in the months of January to April.The average absolute growth rates of mantle length reached (1.175±0.127) mm/d and (0.952±0.213) mm/d for female and male squids respectively.The relationships between mantle length and age,between body weight and age were best described by linear and exponential functions respectively.The female and male growth showed significant differences.The results indicated most of the catch in the traditional fishing ground belonged to the winter-spring spawning cohort.The monthly dominant age class changes the same as time going on,which further confirms the daily deposition of growth increments of O.bartramii.It is deduced that the squid spent about 4-6 months on the migration from spawning ground to feeding ground.