The invention relates to the technical field of forging machines, in particular to an angle-adjustable clamping device. The device comprises a connection die handle and a bending machine upper die connector. An assembly sliding groove is formed in the lower right end of the connection die handle and internally provided with a split clamping plate, the split clamping plate is composed of a left clamping plate body and a right clamping plate body, an upper clamping opening is formed in the joint at the upper end of the split clamping plate, and a lower clamping opening is formed in the joint at the lower end of the split clamping plate. According to the angle-adjustable clamping device, the bending machine upper die connector and an upper connection handle are connected through the split clamping plate, and then a single-side single-action oil cylinder in the assembly sliding groove extrudes and fixes the split clamping plate to the inner wall of the assembly sliding groove, so that the whole clamping device is more convenient to use during loading and unloading, installation requirements are reduced, and later maintenance cost is greatly reduced.