Abstract: In this paper, the coaxiality error of dual-spindle boring and milling machine measured by laser calibrator is studied, and the error factors affecting the measurement results are analyzed. According to the structure characteristics of dual-spindle boring and milling machine, the influences on the coaxiality error are analyzed from three main aspects: column straightness, verticality, and positioning accuracy. Based on the analysis of coaxiality measurement results, it is determined that the direction of deviation of the positioning accuracy of the column and the direction of deviation of the verticality of the column to the table are the main influencing factors. Based on the analysis results, the assembly process of dual-spindle boring and milling machine can be optimized in a targeted manner to reduce the coaxiality error.