The invention relates to a closed loop flexible floating cylinder wave power generation device. The device comprises a closed loop flexible floating cylinder, the closed loop flexible floating cylinder is filled with water, a plurality of check valves are distributed inside the closed loop flexible floating cylinder, the flow direction formed by all the check valves is clockwise or anti-clockwise,and one or more hydro-electric generator sets are further arranged inside the closed loop flexible floating cylinder. According to the closed loop flexible floating cylinder wave power generation device, the closed loop flexible floating cylinder swings along with wave fluctuations, water inside the closed loop flexible floating cylinder is driven to flow, under the effect of the check valves, water flows clockwise or anti-clockwise inside the closed loop flexible floating cylinder, flowing water pushes the hydro-electric generator sets inside the closed loop flexible floating cylinder to generate electricity, irregular wave movements outside the closed loop flexible floating cylinder are converted into regular movements constrained by fluid inside the closed loop flexible floating cylinder, the regular movements are converted into electric energy through the hydro-electric generator sets, and the whole device is simple in structure, high in reliability and suitable for severe sea environments.