This paper presents a method for reliability evaluation of a hybrid generation system of wind and tidal powers with battery energy storage. Such a system may widely exist in coastal areas and islands in the future. A chronological multiple state probability model of tidal power generation system (TPGS) considering both forced outage rate (FOR) of the TPGS and random nature of tidal current speed is developed. In the evaluation of FORs of TPGS and WPGS (wind power generation system), the delivered power related failure rates of power electronic converters for TPGS and WPGS are considered. A chronological power output model of battery energy storage system (BESS) is derived. A hybrid system of tidal and wind generation powers with a BESS is used to demonstrate the effectiveness of the presented method. In case studies, the effects of various parameters on the system reliability are investigated.