High precision inter-satellite velocity measurement technology is one of the key technologies for realizing integration of satellite laser communication measurements and autonomous navigation. We propose an inter-satellite coherent optical communication link velocity measurement method based on modulated code element Doppler measurement. The method adopts a one-way unidirectional approach to obtain phase-continuous code element Doppler signals by using the phase and symbol information of code element symbol synchronization and verdict at the receiver side and by removing the phase modulation information in the baseband sampling data. This can aid in realizing the real-time high accuracy of satellite relative motion velocity while completing inter-satellite communication. The simulation results verify that this method can achieve the relative velocity measurement from 0 to 11.625 km/s at a communication rate of 1 Gbit/s and bit error rate (BER) of 10-9. Furthermore, the velocity measurement uncertainty exceeds 10.00 mm/s.