Narrow line-width lasers were widely used in optical sensing. The frequency drift and noise of lasers directly affect the measurement accuracy of optical sensors. The frequency drift and noise characteristics of narrow line-width fiber lasers and semiconductor lasers were measured by self-timed optical fiber delay method. Firstly, the theoretical calculation of frequency drift measurement was carried out. The relationship between the length of delay fiber and frequency drift was simulated and analyzed, and the length of delay heterodyne fiber was established. Then, a frequency drift test device for narrow line-width laser based on self-heterodyne structure was built, and the composition of the test device was described. Finally, the frequency drift and noise test of narrow line-width laser was carried out based on the test device. The test results show that there is obvious frequency drift in both fiber laser and semiconductor laser. The drift speed is about 2MHz/10s, and the frequency noise of the fiber laser is also lower than that of the semiconductor laser, which is consistent with the measurement results of the frequency noise of the two types of lasers.