With the rapid development of high-speed railway, the railway mobile communication system has more demands on the handover delay and handover success rate. This paper proposes an advance trigger handover algorithm based on the speed in LTE-R. It is designed to suppress communication interruption and dropped calls caused by that the signaling interaction and setting pre-bearer switching point get rise to handover too early or too late. The theoretical analysis is established in the signaling flow chart, and it is shown that the advance handover algorithm can shorten the handoff latency, which TDD frame structure type two has the most significant time effect. Finally, the simulation shows that compared with the conventional handover algorithm, the advance handover algorithm has a higher and more stable handover success rate. It provides a technical support for the future railway private network applications to LTE-R.