Time synchronisation is one of the key issues to realise remote detection for multi-static radar. With the condition that the receivers are commonly located at different distances from the transmitter, a high-precision time synchronisation scheme for multi-static radar with mixed microwave and troposcatter channels is proposed. In order to prove the feasibility of transmitting pulse signals in microwave channel, the jitter of the signals has been tested, and the transmission loss of the troposcatter channel has been calculated. Finally, the accuracy of the proposed model is analysed, which shows that the proposed scheme is feasible and can be a backup for time synchronisation for multi-static radar.