A dispersion measurement prototype is designed based on the modulation phase shift method, which improves the accuracy and reduces the cost of dispersion measurement. In addition, the dual phase discrimination circuit is designed based on the amplitude and phase detection chip AD8302 and the accurate measurement of phase difference is realized. The least square method is used to fit the received data and a reliable dispersion coefficient curve is obtained. The modular design is adopted as a whole. The digital signal processing based on chip F2812 is also used to accomplish the control to the board of each module as well as the collection and processing of data. The interface is designed on the LabVIEW development platform. The performance of the prototype is verified by experiments and the results show that the uncertainty of the cumulative dispersion measurement at wavelength of 1550 nm is less than 10 ps/nm for the G.652 fibers with different lengths.