In this paper, we address the problem of energy efficient resource allocation in multi-cell full-duplex distributed antenna systems (DAS). Considering the user's quality-of-service (QoS) requirements and per-RAU and per-user power constraints, we jointly optimized the uplink and downlink beamforming factors, user transmit power, and remote antenna unit (RAU) selection to maximize system energy efficiency. Firstly, the objective function is converted from fractional order form to subtraction form through fractional programming, and an iterative resource allocation algorithm is proposed, which needs to solve internal problems in each iteration. Then, using hierarchical decomposition and successive convex approximation, the internal non-convex problem is transformed into a series of iterative convex optimization problems. Simulation results show that the proposed algorithm can significantly improve energy efficiency.