Abstract: The alternating measurement mode roadheader positioning technology will produce cumulative measurement error in the process of multiple alternating measurement, which will affect the positioning precision of roadheader. At present, the research mainly focuses on the causes of single measurement error, error distribution law and error reduction methods, but there is no research results on the error distribution law of multiple alternating measurement. By analyzing the working principle and positioning process of alternating measurement mode roadheader positioning system, the positioning error model of roadheader is established. The accuracy of the error model is verified by the graphic method, and the results show that the positioning errors obtained by the graphic method and the error model are basically the same, and and there are only 10⁻³ orders of magnitude errors between them. The impact of angle measurement error, distance measurement error, moving step length and distance between the roadheader and measuring platform on roadheader positioning error is studied by error model. The results show that the larger the angle measurement error, the larger the curvature of the positioning error curve, that is, the faster the error grows. And the Y_T axis positioning error grows faster than the X_T axis. The distance measurement error has a greater impact on the X_T axis positioning error, and the smaller the distance measurement error, the smaller the initial X_T axis positioning error. However, the error change speed is not affected. As the moving step length increases, the Y_T axis positioning error curvature increases, that is, the Y_T axis positioning error growing speed increases. The impacts of the distance between the roadheader and measuring platform and the moving step length on roadheader positioning error are basically equivalent. The orthogonal test method is used to analyze the impact degree of each factor on the positioning error of roadheader. The results show that the distance measurement error has the greatest impact on the positioning error of the X_T axis, followed by the angle measurement error. The moving step length and the distance between the roadheader and the measuring platform have the smallest impact and the two have the same degree of impact. The angle measurement error has the greatest impact on the positioning error of the Y_T axis, followed by the moving step length and the distance between the roadheader and the measuring platform, and the impacts of the two are the same. The impact of the distance measurement error is the smallest. The range analysis method is used to obtain the optimal parameter combination to reduce the positioning error.