Abstract: For downlink Energy-harvesting small cell networks, a coalitional game-based optimal resource allocation algorithm is proposed in this paper to improve system capacity and energy efficiency. First, the energy-harvesting small cell network model is established, in which small cells are connected by transmit lines and hold the ability to transfer energy. Then, based on the proposed time and energy strategy, a decentralized coalition formation algorithm is presented, and the small cell transmition power is adjusted. For ensuring the convergence of the algorithm, the small cell transition rules are put forward to control the coalition formation, which would also guarantee the optimization of the game. The simulation results show that the proposed algorithm could enhance the system frequency efficiency by sharing harvesting energy and the satisfaction of service is also demonstrated to be improved.