Abstract: In this paper, the optimal power allocation problem of two-way relay channel (TWRC) system with analog network coding (ANC) is discussed with asymmetric transmission requirements. The paper provides the closed-form expressions for optimum power allocation in terms of minimum outage probability and maximum sum-rate respectively. It also shows that the two types of optimum power allocation schemes are exactly the same. The analysis indicates that some existing optimal power allocation schemes of TWRC with ANC are special cases of the proposed scheme. Moreover, simulation results show that the achievable outage probability and sum-rate performance of the proposed unified optimum power allocation scheme outperforms that of the uniform power allocation scheme.