In mobile ad hoc & sensor networks, power control is an efficient way to improve the efficiency of energy. However, it will also produce negative influence on many aspects of the networks such as the network connectivity, delay and network capacity. In this paper, proposed related energy control mechanisms for ad hoc & sensor networks are introduced. Considering the QoS requirement such as maximum network capacity, minimum network radius and guaranteed network connectivity, a power control model based on non-cooperative game theory is given. And a distributed non-cooperative game algorithm to power control for ad hoc & sensor networks is presented. The existing and uniqueness of Nash equilibrium for the algorithm is also proved in this paper. Finally simulation experiments are implemented to verify the algorithm. The results show that the algorithm is efficient and has a good integrated performance.