Abstract: In this study, according to the survey data of tuna purse seine by sea trials from 2011 to 2014, by using the Bootstrap and generalized additive model(GAM)to quantitatively analyse the differences gear performance between free swimming school and floating objects fishing methods.The results show that:(1)the maximum sinking depth of floating objects fishing method(195.20-219.36 m)is 94.8% of free swimming school fishing method(205.83-219.04 m);The average sinking speed of the floating objects fishing method(0.152-0.176 m/s)is 84.4%-91.2% of free swimming school fishing method(0.180-0.193 m/s).(2)V₁₀, V₆₀ and L₁ have a significant impact on the sinking speed for the swimming school fishing method.(3)V₆₀, L and V₀ have a significant impact on the sinking speed for the fishing floating objects associated school.(4)The results by GAM prediction show that:the predicted values of sinking speed(0.155-0.175 m/s)is 99.4% of sea trials for the floating objects fishing method;the predicted values of sinking speed(0.182-0.190 m/s)is 98.4% of sea trials for the free swimming school fishing method.These results can provide some reference for distinguishing the sea conditions and controlling the fishing operation for sea operation.