With regarding the rotation rate of one fully hydraulic drilling rig as the research target，by using the statistical analysis software of Minitab（16.0）and basic theory of experimental design method，the quality characteristic value including safety valve discharge outlet flow，circuit board outlet diameter and damping screw opening depth were selected as the influencing factors, according to load test of three factor and three level in the drilling rig, and by measuring the different rotational speed value that corresponded to the different factor levels combination， the optimal factor combination is found by influence law analysis of different factor to output speed. Through the factor analysis，variance analysis and regression analysis, safety valve discharge outlet flow and circuit board outlet diameter were identified as key factors that influencing output speed, and regression equation of output speed was established. This provides references for design of the hydraulic system and quality assurance of drilling rig.