Edge Computing (EC) and Simultaneous Wireless Information and Power Transfer (SWIPT) technologies can improve the performance of traditional networks, but they also increase the difficulty and complexity of system decision-making. The system decisions designed by optimization methods often have high computational complexity and are difficult to meet the real-time requirements of the system. Therefore, aiming at Wireless Sensor Network (WSN) assisted by EC and SWIPT, a mathematical model of system energy efficiency optimization was proposed by jointly considering beamforming, computing offloading and power control problems in the network. Then, concerning the non-convex and parameter coupling characteristics of this model, a joint optimization method based on deep reinforcement learning was proposed by designing information interchange process of the system. This method did not need to build an environmental model and adopted a reward function instead of the Critic network for action evaluation, which could reduce the difficulty of decision-making and improve the system real-time performance. Finally, based on the joint optimization method, an Improved Deep Deterministic Policy Gradient (IDDPG) algorithm was designed. Simulation comparisons were made with a variety of optimization algorithms and machine learning algorithms to verify the advantages of the joint optimization method in reducing the computational complexity and improving real-time performance of decision-making.