In this paper, we propose Split Multi-path Routing protocol with Load Balancing policy (SMR-LB) to improve TCP performance in mobile ad hoc networks. In SMR-LB, each intermediate node records how many primary paths are attemped to construct as well as the source ID which attempts to construct the primary path. Each intermediate node decides which primary path should be constructed by using the primary path and the source ID information. As a result, SMR-LB can utilize the load balancing policy to reduce the probability of congestion and avoid the continuous link breakages between the specific source and destination pair. We show that SMR-LB can improve TCP performance compared with the conventional protocols by computer simulation.