The tolerance analysis methods are usually used to test the result of product design and assembly; moreover the tolerance analysis also is a fundamental technique in precision design process. So far, there are two kinds of tolerance analysis methods: statistical tolerance analysis and worst-case analysis; they have their own characteristics and drawbacks. In this paper, it presents a nonlinear tolerance analysis method which uses Matlab tool to construct the nonlinear tolerance analysis mathematical formulation and calculate the result of nonlinear tolerance analysis based on the principle of worst-case tolerance analysis. All the processes are dealt with and tested by computer. The engineers only enter some basic parameters through the standardized interface, and then the result can be obtained without artificial intervention. In addition, the accuracy of calculation result meets the production requirement. The system of the nonlinear tolerance analysis is easier for engineers to use.