Abstract: In order to study effect of laser sources with different linewidthes on positioning accuracy of Mach-Zehnder fiber interferometers, a set of disturbance location system was built using the principle of mutual-correlation positioning algorithm.3kHz and 1MHz semiconductor lasers were used as system output light sources respectively, and were subjected to multiple fixed-point disturbances.The experimental data were calculated according to the principle of mutual correlation, and the results were compared and analyzed.The results show that, in the case of time domain sampling rate of 100MHz, average positioning error of 3kHz laser is 34.4m, far less than positioning error of 225.4m for 1MHz light source.The method of using 3m single-mode fiber in the signal arm of the interferometer to make the signal arm and the reference arm basically the same length, largely suppresses the common-mode noise of the system.Narrow linewidth laser can improve the positioning accuracy of the system.The study has positive significance for the selection of interferometer lasers and the evaluation of system performance parameters.