介绍了全站仪测量既有铁路线路时,采用坐标法计算曲线拨距的理论推导,以图文形式将渐伸线原理与坐标法计算的精度进行对比,体现了坐标法计算的优越性。指出坐标法计算曲线理论严密、计算精度高、操作灵活,具有较高的推广价值。 This paper introduces the theoretical derivation of calculating the curve distance by using the coordinate method when measuring the existing railway lines by using the total station. Comparing the accuracy of the involute line calculation method and the coordinate method in the form of text, it shows the superiority of the coordinate method calculation. It is pointed out that the calculation method of coordinate method is rigorous, the calculation precision is high, the operation is flexible, and it has high popularization value.