The tooth surface of spiral bevel gear is complex.In order to study the sensitivity of machine tool geometric error to tooth surface deviation,based on the establishment of spiral bevel gear tooth surface machining deviation model,the local sensitivity analysis method and Sobol global sensitivity analysis method were used respectively,to study the influence of input parameter range change on the output result.The key geometric error affecting tooth surface deviation was determined.The characteristics of the two analysis methods were compared from two aspects of input parameters and output results.The selection principle of sensitivity analysis method was defined:for the model which distribution range of input parameters is not clear,or the linear or nonlinear distribution is similar,local sensitivity analysis can be considered;for nonlinear models with complex distribution of input parameters and high accuracy requirements,global sensitivity analysis method is suitable.