Most of the proposed routing protocols for Wireless Sensor Networks (WSNs) concentrate on efficiently using constrained resources, especially the energy. However, one important factor of the routing protocols, QoS routing, has not been paid enough attention. Transmission collision appears frequently at nodes that receive packets from multiple nodes. Consequently, the network performance is greatly reduced. Furthermore, frequent collisions increase delay, which is important to real-time applications. The services provided by the sensor network are also impacted. In this paper, we propose a mechanism to find multiple paths between one sink and multiple sources with the consideration of reducing collision. We take advantage of the mass deployment of sensor nodes to search for disjoint paths for multiple source nodes in order to avoid collisions. Besides the increase in the network lifetime and throughput, the protocol also decreases the latency. Simulation results are provided to demonstrate the effectiveness of our solution.