Fishing effort is the effort invested in fishery by the same operating method within a period of time.The traditional expression for fishing effort of trawlers is in time and power or tonnage and time.There are 40 thousand vessels installed with terminals of Beidou Satellite Navigation System in China.The vessel position information has a temporal resolution of 3 minutes and a spatial resolution of 10 meters, from which fishing effort can also be extracted.Computation for traditional fishing effort statistics takes much time and effort, and the fishing intensity in macro dimension cannot be accessed in real time.By mining the data from the Beidou satellite ship position monitoring system, such as the position, course, speed and other information of fishing boat, the fishing effort might be explored.In this paper, the speed thresholds of every fishing boat which reflect their fishing condition are obtained by the statistics of vessel speed under steam and trawling.And fishing state points can be judged by combining the speed threshold and heading deviation.The fishing state of trawler 300791 has heading difference and speed thresholds.Minimum and maximum thresholds of heading difference are -50 and 52°.Minimum and maximum thresholds of speed is 0.9 and 2.0 m/s.Via the correction of the filtering window, the fishing area grid is calculated by the accumulated fishing time in fishing state point of each boat.The fishing effort is the product of the accumulated fishing time and the fishing boat power, such as kW·h.And the lattice figure and interpolation of the accumulated fishing are made.This method has the characteristics of real-time, large-scale, fast speed and high resolution, which can provide good reference for the protection of fishery resources.