We evaluated the relationship between the rate of fishing success and the sinking performance of purse seines operated by a Chinese tuna purse seine fleet from 2006 to 2012. The 95% confidence intervals for maximum sinking depth (D) and average sinking speed (S) of the middle part of gear ranged from 195.3 m to 209.3 m and from 0.181 m/s to 0.192 m/s, respectively. The data obtained from at-sea observations indicate there is a significant difference in the fishing success among the different sinking speeds. Fishing success increased rapidly from 20.0% to 66.7% with an increase in the sinking speed. However, there was no relationship between fishing success and sinking depth. An initial run of the full logistic regression model revealed that the sinking depth is not a significant factor of fishing success (P>0.01), i.e. the probability of fishing success depends only on the sinking speed of the fishing gear. Moreover, fishing successes at different speeds predicted by the model were similar to the at-sea observations. Our results suggest that more effort should be made to accelerating the sinking speed but not deepen the sinking depth of fishing gear.