Abstract: In order to meet the real-time and accurate monitoring and early warning of geological disasters, and in view of the fact that the traditional GNSS carrier phase difference speed measurement mainly adopts the post-event simulation real-time processing mode, the post-event GNSS carrier phase difference speed measurement program is improved. Added the function of real-time data stream reception and real-time decoding of the RTCM to meet the needs of real-time speed measurement. Use the static station experiment and the shaking table to simulate the sine wave vibration experiment to evaluate the accuracy of the improved GNSS real-time speed measurement program. The root mean square (RMS) of the error in NEU directions in the static experiment is better than 5 mm/s; the RMS difference between the calculated speed in NEU directions and the true value in the dynamic experiment is 10.4 mm/s. It shows that the speed measurement accuracy of the real-time GNSS speed measurement program in this experiment can reach millimeter level under static real-time speed measurement conditions, and the speed measurement accuracy can still reach centimeter level under real-time dynamic conditions.