Abstract: A flexible water pipe, including: an inner pipe, which can extend or contract when water-filling or dewatering in the flexible water pipe; an outer pipe, which can unfold or wrinkle when water-filling or dewatering in the flexible water pipe; several rings arranged outside the inner pipe; a joint in inflow side, which is used to fasten the inner and outer pipes in inflow side; and a joint in outflow side, which is used to fasten the inner and outer pipes in outflow side; wherein, the outer pipe is arranged outside the inner pipe and the ring.