The invention discloses a hydraulic indexing clamping device capable of rapidly replacing a workpiece and fast in transposition. The hydraulic indexing clamping device is structurally characterized by comprising a fixing base, a rotating assembly, a positioning assembly, a pressing assembly and a hydraulic rotating connector. The fixing base comprises a disc connecting part, an upper base plate, a middle base plate and a lower base plate. The rotating assembly comprises a rotation shaft, a swing hydraulic cylinder, an overrun clutch and an anti-rotation assembly. The swing hydraulic cylinder drives the rotation shaft to rotate in one direction through the overrun clutch. The positioning assembly is used for preventing the rotation shaft from rotating during machining. The anti-rotation assembly is used for multiple times of continuous rotation of the overrun clutch, and the rotation shaft is prevented from reversely rotating. The pressing assembly comprises a second hydraulic cylinder, a thrust ball bearing and a pressing disc. The fixing base is fixedly arranged at the right end of a machine tool main shaft installing base through the disc connecting part of the fixing base. The hydraulic rotating connector is arranged at the left end of the machine tool main shaft installing base. Corresponding oil outlets of the hydraulic rotating connector are communicated with the swing hydraulic cylinder and the first hydraulic cylinder through corresponding pipelines.