Abstract: In order to adapt to the fast change of the network topology, easy link fracture, the unidirectional link and the load imbalance in tactical Internet mobile subnet, the traditional AODV protocol is improved. Stability of link and load of nodes considered in routing choose, the forward nodes list to be added to RREQ message to avoid unidirectional links and main and backup routes stored by the source node, the MSAODV (Mobile Subnet based on AODV) routing protocol has been designed for battlefield environment. OPNET simulation results show that the MSAODV protocol can improve tactical internet performance.