In two-phase cooperative multicast communications, the unbalanced outage probabilities of the cell-center and cell-edge users are the main reason that caps the energy-efficiency of the system. In this paper, we consider the unbalanced outage probability and propose a probability-based relay selection and power control method to improve the energy-efficiency, in which each user can autonomously decide whether to participate in the relay transmission. In particular, we obtain the optimal solution that can minimize the user power consumption. In addition, since our method works in a distributed manner, it does not require any feedback either between the BS and users, or among the users. This saves the extra energy consumption caused by the feedback. Simulation results demonstrate that the proposed method can reduce the user energy consumption up to 54%.