basis of the data collected from October 2010 to January 2011 in the tuna longline survey, the soak time calculation models of every branch line in each operation were developed by both modes of hook retrieval. The soak time of longline gear divided into one hour interval for the quantity of hooks and the individuals of bigeye tuna (), respectively. The respective catch rates (CPUEs) of bigeye tuna and yellowfin tuna in each hour interval were calculated. The results showed that (1) both CPUE of bigeye tuna and yellowfin tuna presented increasing at first and then decreasing trend along the increase of soak time. The reason was the lure effect fluctuation of bait and the lose of hooked fish; (2) the quadratic curves can be fit the relationships between soak time and the CPUE of bigeye tuna, and yellowfin tuna; (3) the CPUE of bigeye tuna and yellowfin tuna was the highest when soak time was 9.9 h and 10.1 h, respectively. This study suggested that (1) the soak time of each hook lasted about 9.510.5 h in the tuna longline operation for improving the fishing efficiency and decreasing the bycatch; (2) the soak time of the longline gear could be considered as the effective fishing effort and used to standardize the CPUE.improve the fishing efficiency and to decrease the bycatch and will be for the references to the fishing strategy and CPUE standardization.