A sample clamping device for conducting a fracture test through a cold bending machine is mainly composed of a fixing frame, a first sample carrying frame, a second sample carrying frame, an inverted-trapezoid-shaped test groove, a positioning opening, a positioning edge and a connecting plate. The first sample carrying frame and the second sample carrying frame are connected to the fixing frame and symmetrically arranged. The inverted-trapezoid-shaped test groove is formed between the first sample carrying frame and the second sample carrying frame. The positioning opening is formed in the bottom of the inverted-trapezoid-shaped test groove. The positioning edge is installed in the positioning opening. The connecting plate is connected to the part, under the inverted-trapezoid-shaped test groove, of the fixing frame. The first sample carrying frame and the second sample carrying frame are symmetrically arranged with the central line of the fixing frame as a reference. The positioning opening is formed in the central line of the inverted-trapezoid-shaped test groove. By means of the sample clamping device, it is achieved that both a cold bend test and a steel plate fraction test can be conduced on a common cold bending test machine, a fracture sample can be stably arranged and can be fractured, and a test result is accurate. The whole fracture test process is completed in the sample clamping device; furthermore, due to the fact that the inverted-trapezoid-shaped test groove is formed, it is ensured that a pressure head of the test machine does not collide with the device in the test process.