Aiming at the special communication network service system, in order to transmit 1 channel of standard G.729 Voice over Internet Protocol（VoIP）voice data over 10 kb/s narrowband channel in the special communication scenario, a hybrid speech compression coding algorithm based on IP packet splitting and reassembling technology is proposed. The algorithm decomposes the voice data after G.729 compression, and then performs secondary compression through Advanced Multi-Band Excitation (AMBE). Combined with IP packet splitting and reassembly technology, the payload in the voice data is retained, the redundant overhead data is eliminated, and the bandwidth required for voice data transmission is reduced. The effectiveness of the method is verified by simulation experiment. The experiments show that when the speech compression coding rate of G.729 and AMBE is 8 kb/s and 2.4 kb/s respectively, the load length is 20 ms, and the IP packet packaging cycle is 8 packets, the average sentence intelligibility is above 85% and the voice signal level is above level 3 under any optical path state, which meets voice transmission system requirements.