Wireless ad hoc networks suffer from link unreliability and high packet loss rate. To reduce the number of sending data packets in unreliable multihop wireless networks, a network coding based routing protocol with path switching, NCPS, is proposed. To ensure the paths are suitable for network coding, this study first analyzes the sufficient conditions that paths in wireless network can be encoded and decoded. Next, it analyzes the coding gain with path switching in contrast to the traditional optimal routing algorithm. Finally, in order to optimize the data packet transmission times in wireless networks, it proposes a routing protocol which combines path switching and network coding. Experimental results show that under different environmental parameters of networks, NCPS can reduce the number of data transmission in network effectively and obtain stable coding gain.