For the problem of stable and continuous power supply for underwater sensor networks,a simulation analysis of the piezoelectric energy harvester of a piezoelectric cantilever built into a flexible tube was carried out.The experiment conducted fluid-structure coupling simulation of the single-energy-harvester,the pre-flexible and rigid bluff bodywere carried out respectively.Then,the piezoelectric coupling and collecting circuit simulation analysis was carried out on the pre-bluffing energy harvester.The results show that the amplitude response of the energyharvester of the front rigid bluff body was greater than that of the front flexible bluff body and the single-energy-trapping structure.When the flow velocity was 1.1 m/s,the L/D was 3~4,the generated amplitude response and voltage amplitude were 0.9 mm and 85 V respectively.At this time,the frequency was 9 Hz,and the energy collection efficiency was 36.18%,which was the highest of the vortex-induced vibration piezoelectric energy harvester.It proved the feasibility of the piezoelectric energy harvester with the piezoelectric cantilever beam built into the flexible tube,and provided a solution for the continuous and stable energy supply of the underwater sensor network.