Based on the catch amount data of Chinese squid jigger vessels from January to July 2006 and the sea current, sea surface temperature (SST) and chlorophyll-a (chl-a) data derived from satellites, the characteristics of Illex argentinus fishing grounds, their productivity, and environment factors in southwest Atlantic were analyzed. There were two main I. argentinus fishing grounds in southwest Atlantic, one in its south part (60 degrees 30' W, 45 degrees 30' S) and the other in the north part (58 degrees 00' W, 42 degrees 00' S). From January to July, the main fishing grounds migrated from south to north. The productivity fluctuated notably in different months, being higher from January to April and the highest in March. After May, the productivity decreased gradually. The locations of the fishing grounds had close relationships with Falkland cold current. North fishing ground located at the main axis of the current, with a current speed of about 28-60 cm x s(-1); and south fishing ground located at the west of the current, with a small scale anticyclone and a current speed of about 5-32 cm x s(-1). The favorable SST in the fishing grounds was 7 degrees C-15 degrees C, with a favorite SST of 12 degrees C, and the favorable chl-a concentration was 0.4-1.5 mg x m(-3), with a favorite chl-a concentration of 0.9-1.2 mg x m(-3). A significant positive relationship was observed between I. argentinus productivity and chl-a concentration (P < 0.05).