Abstract: The network architecture and the heterogeneity of hybrid energy supply will lead to extreme imbalance of load distribution in 5G small cell base stations (SBS), which causes the waste of resources. A new challenge is faced about how to utilize renewable energy and radio resource efficiently. In this paper, an approach of user association mechanism and resource allocation strategy is proposed for a given communication rate. In order to minimize the total energy of system, the bias factor of the SBS ’ favorite is used to describe the extent of user association, and an estimation algorithm of energy hungry probability is presented for uncertainty reduction in energy by utilizing the large deviation theory. Moreover, the resource allocation strategy is proposed to allocate band resource reasonably through the Lagrange dual algorithm. Numerical simulation results show that the energy consumption of the proposed algorithm can reduce 82.47% than that of the maximum received power algorithm. Also, the utilization rate of green energy of the proposed algorithm will increase 48% than that of the maximum channel gain algorithm.