Abstract: The principle of operation, design, construction and measured results of time-domain measurement system using pulse spreading are presented in this paper. All of the elements and devices used in this system are made in China. The system can be used to measure single-mode fiber dispersion at longer wavelength (1.3μm). It is shown by the measured results and analyses that the system is applicable to multi-mode fiber dispersion measurement and photodeteotor response time measurement with high accuracy. For single-mode[fiber dispersion measurement, the relative error can be better than 3% if the test fiber is longer than 10km. When the test fiber is shorter, the relative error becomes worse. However, it is still applicable to identify whether a single-mode fiber meets the dispersion specification of 6ps, kru-nm at 1.3μm wavelength region.