With the continuous growth of global energy demand and the depletion of non-renewable resources, the role of power electronic converters in energy conversion and distribution has become increasingly significant. This paper addresses the modulation strategy for the Dual Active Bridge (DAB) converter under complex operating conditions, proposing an optimization method based on reinforcement learning (RL). By incorporating Deep Q-Network (DQN) and Double Deep Q-Network (DDQN) algorithms, an intelligent agent control system is designed. The agent learns and optimizes the phase-shift modulation strategy through interactions with the DAB circuit environment, aiming to achieve high efficiency and stability in power transmission. Simulations conducted using MATLAB demonstrate that the RL-based DAB modulation strategy significantly enhances stability and self-stability compared to traditional control strategies across various operating conditions. The proposed RL-based control strategy for DAB converters offers a novel approach to overcoming the limitations of conventional control methods in complex scenarios. It not only enhances the performance of DAB converters but also provides new research perspectives and theoretical foundations for the intelligent control of power electronic converters.