Abstract: The effect law between the machine adjustment parameter errors and surface errors of the hypoid gears by SFT(spiral format tilt) was researched.Based on the gear meshing theory,the equations of theoretical tooth bearing and error tooth were established,the analytical expression of tooth surface processing errors caused by the machine adjustment parameter errors was derived,and the concept of error influence coefficient was proposed.The impact of surface errors caused by machine adjustment parameter errors can be obtained according to the error influence coefficient.By comparing the theoretical tooth bearing with error tooth,the effect law of the whole tooth surface law errors caused by the machine adjustment parameter errors was determined.The major impacts of the machine adjustment parameter errors were determined by the analytical and numerical method.The content and methods of this research provide a theoretical basis and practical guidance to compensate the machine adjustment errors for the spiral bevel gears surface errors.