The invention discloses a hydraulic device with a hooked shell formed by a bi-conical shell, which can be used for solving the design problem of hydraulic assembling for forming the bi-conical shell into an arc-shaped hooked drum. The hydraulic device comprises an outer cylinder mold (1), a conical core (7) and a bi-conical shell (14), wherein an inner hooked chamber (2) is arranged in the outer cylinder mold (1); the conical core (7) is arranged in the outer cylinder mold (1); a workpiece forming inner chamber (13) is formed between the outer cylinder mold (1) and the conical core (7); the bi-conical shell (14) is arranged in the workpiece forming inner chamber (13); an upper end sealing ring (15) is arranged at the top end of the workpiece forming inner chamber (13); a lower end sealing ring (18) is arranged at the bottom end of the workpiece forming inner chamber (13). According to the invention, the thin-wall forming of various irregularly shaped cylindrical workpieces can be realized; the forming effect is good; the processing cost is low; the hydraulic device can meet the requirement of volume production.