In order to solve the extra power consumption caused by reducing complexity in cooperative relay networks, an optimized power allocation algorithm is proposed for the efficient incremental selection hybrid decode-amplify forward (ISHDAF) scheme. In the ISHDAF scheme, the transmission efficiency is improved by optimizing the power allocation, which is constrained by constant total power. And the outage probability is used as the objective function to optimize the whole power allocation. Then, rational allocation of the power of source and relay nodes can be obtained by the optimization of equal power allocation algorithm in the power limited wireless communication system. Simulation results show that the outage probability of a relay network is effectively reduced by the proposed scheme for the ISHDAF relay network. For an instance of a total power of 40W, there is a certain optimization of outage probability, when compared with that of the current HDAF scheme. Therefore, the proposed power allocation algorithm for the ISHDAF scheme can be effectively applied to optimize the power consumption in the relay network systems.