针对影响激光测量直线度误差的主要因素之一激光光线漂移，提出了一种基于共路光线漂移补偿的直线度误差测量方法，给出了具体的测量原理和系统构成。从产生激光光线漂移的几个因素出发，理论分析了所产生的光线漂移对直线度误差测量的影响，建立了相对应的光线漂移补偿模型。结果表明，进行补偿后激光器出射光线引起的光线漂移在X方向的最大漂移量由28.4 μm减少为5.6 μm，Y方向的最大漂移量由21.6 μm减少到5 μm；由温度梯度引起的光线漂移经补偿后最大漂移量由65.7 μm 减少为8.9μm。实验结果与理论分析均表明，该方法能有效减少各种因素引起的光线漂移对直线度测量结果的影响，提高测量直线度误差的准确性。

The laser beam drift is one of the key factors that influence on the accuracy of laser measurement of straightness errors, and a novel method for straightness error measurement based on common-path compensation for the laser beam drift was proposed. The measurement principle and system configuration were given, influences of the laser beam drifts caused by different factors on straightness error measurement were analyzed，and a compensation model was established.After compensation,the results show that the variation of emission beam is reduced from 28.4 μm to 5.6 μm and from 21.6 μm to 5 μm in X direction and in Y direction, respectively,and the variation of beam drift due to temperature gradient is from 65.7 μm to 8.9 μm. Both experimental results and theoretical analysis show that the common-path compensation for the laser beam drift method can decrease greatly the influences of the laser beam drift on the straightness error measurement, and can enhance its measurement accuracy.