提出了一种用于绝对距离测量的光纤超外差干涉系统，简述了该方案的原理，给出了信号处理的框图，并进行了初步实验。对系统的误差分析表明，在光强较弱、信噪比差的情况下，光学元件的非理想特性以及测量信号与参考信号之间的耦合是引起测量误差的主要原因。 A superheterodyne fiber super-heterodyne interference system for absolute distance measurement is presented. The principle of this scheme is briefly described. A block diagram of the signal processing is given and a preliminary experiment is carried out. The error analysis of the system shows that the non-ideal characteristics of the optical element and the coupling between the measurement signal and the reference signal are the main causes of the measurement error in the case of weak light intensity and poor signal-to-noise ratio.