In the design of trawlers, it is necessary to consider the matching between the propeller-hull-engine, and the matching between the netting gear-hull-engine-propeller so as to realize the high efficiency of propulsion system. This paper introduces the time probability parameter optimization method to determine the optimum propeller, and realize the best operating conditions to achieve comprehensive efficiency and reasonable matching between the propeller-hull-engine through the optimization analysis of the limitation in design of trawlers. 30 trawlers operated in good conditions were selected from the trawler database for the calculation of effective drag force to establish a multivariate nonlinear regression equation involving effective drag force of the netting gear and the power and drag speed of the main motor; netting gears and the otter boards were selected based on the effective drag force calculated according to this equation so as to achieve a reasonable matching between the effective drag and fishing gear with the final goal to realize the reasonable matching between the netting gear-hull-engine-propeller. The error range and applicability of the effective drag force estimation formula were verified by the comparison with the calculation results of real ships. At the beginning in the design of trawlers, the formula can be used to estimate the effective drag force to realize the matching between fishing gears and otter boards and the technical and economic optimization demonstration can be realized with the final goal of the optimal matching between the hull-engine-propeller-netting gear.