Abstract: The traditional error modeling method does not consider the error distribution.Therefore, based on the analysis of the traditional error modeling methods.This paper proposes a homogeneous coordinate transformation method including the second moment information of the error. The distribution of the errors of the machine tool is expressed in the form of the mean value and standard deviation matrix. The spatial positioning error of the machine tool is expressed in the form of interval. Finally, the correctness of the model is verified by comparative experiments. Compared with the traditional error model, the error model can more accurately express the spatial positioning error of machine tool. It provides a reference for the improvement of machine tool accuracy.