提出了一种采用双纵模稳频激光器的新型绝对距离测量外差干涉仪。该干涉仪探测两个波长各自的外差信号， 通过测量两信号的相位差， 直接测量出合成波的小数级次。指出了两波长间的相互耦合对测量精度的影响， 提出了补偿方法， 在２５ ｍ 的测量范围取得了 １４０ μｍ 的测量精度。 A new type of absolute distance measurement heterodyne interferometer with dual longitudinal mode frequency stabilized laser is proposed. The interferometer detects the heterodyne signals of the two wavelengths respectively and directly measures the fractional order of the synthesized wave by measuring the phase difference between the two signals. The influence of mutual coupling between two wavelengths on the measurement accuracy is pointed out. The compensation method is proposed, and the measurement accuracy of 140 μm is obtained in the measurement range of 25 m.