Hydrostatic guideway is the core of five-axis ultra-precision machine tool.Straightness error of the guideway will be directly reflected in the processing of parts,impacting product interchangeability and product accuracy.Straightness is an important indicator of the accuracy of the machine.In the guideways installation process,the straightness of the guideway must be measured.Therefore,it is very important to analyze the straightness error and to research the algorithm.Visual analysis of the collected discrete data by MATLAB can not only guarantee the correctness of the operation but also provide a very intuitive observation of the shape of the guideway.