In order to solve the problem of the high complexity of channel encoding/decoding algorithms and real equipment for the networking coding system with LDPC code or Turbo code in two way relay channel, a new combination scheme of Polar channel code and physical network coding is proposed. This scheme utilize the superposition of wireless signals and the linear property of Polar code and network coding to estimate the network codeword directly, thus reduce 50% the decoding complexity of relay node and 50% the information exchange time between source nodes than that of the direct network coding. Simultaneously, Polar code which based on the channel polarization can achieve channel capacity on BDMC with low complexity of encoding and decoding algorithms, so the proposed scheme can be applied easily with reliability, and the simulation results also verified the effectiveness of the scheme.