The integration of tidal energy and offshore wind power generation systems on a single monopile represents an innovative co-generation system. The energy storage system plays a crucial role in mitigating the inherent intermittent fluctuations of the microgrid systems integrated by these sources. In a DC microgrid hybrid energy storage system (HESS), the state of charge (SOC) of supercapacitors and batteries is prone to exceed limits during operation. Supercapacitors with smaller capacities, when they reach their limits, may prevent batteries from independently smoothing the system power fluctuations. An improved limit strategy is proposed on the basis of traditional limit strategy; the terminal voltage of supercapacitor is pre-controlled, and the output power of supercapacitor is modified according to the residual capacity and charge-discharge state of supercapacitor. By analyzing the characteristics of wind speed and tidal flow velocity and combining short-term power prediction methods to assess power fluctuations, a storage control strategy based on short-term power prediction is proposed. This strategy considers both the system’s power fluctuations and the SOC of the energy storage system at the next moment, proactively adjusts the battery output when the supercapacitor is constrained. The proposed method is verified by the simulation.