According to the sampled squid, Dosidicus gigas, collected from the fishing and survey by Chinese squid fishing boats for many years off EEZ of Peru, Chile and Costa Rica, the biological characteristics of D. gigas form three different fishing areas are compared. The results indicated that their mantle lengths of D. gigas off EEZ of Peru, Chile and Costa Rica ranged from 209 to 1 149 mm, from 166 to 837 mm and from 204 to 429 mm respectively, their dominant mantle lengths were 250-400 mm ,300-450 mm and 250-350 mm accordingly, and their average sex ratio in the catch were 3.87∶1, 2.50∶1 and 3.75∶1 respectively. Based on the mantle length composition and sexual maturity, it is suggested that three groups including largesized, mediumsized and smallsized groups that existed off EEZ of Peru, the main mediumsized group and a small group of largesized group are distributed off EEZ of Chile, and the main smallsized group and a small amount of mediumsized groups existed off EEZ of Costa Rica. Off waters of Peru and Chile, the value of growth parameters for the relationship between body weight and mantle length reached 3.06-3.17, while off waters of Costa Rica the value is 2.57-2.63. Off waters of Peru and Chile, the maturity stage of D. gigas mainly composed of stage Ⅰ and stage Ⅱ, while off waters of Costa Rica stages Ⅱ, Ⅲ and Ⅳ are dominant. The changes in monthly feeding level have significant difference, but the levels from 0 to 2 are the main. It is concluded that the population structures and biological characteristics of D. gigas in the three fishing areas have a difference as a whole.