The invention discloses a sample, a clamp and a method for a plate compression performance test. The sample is provided with two first force bearing pinholes and two second force bearing pinholes. Themiddle of the sample is provided with two L shaped grooves. The inner connection sections of two L shaped grooves are set to be the sample ranging sections. The clamp comprises a front clamping plateand a rear clamping plate. The front clamping plate comprises an upper front clamping plate and a lower front clamping plate. The rear clamping plate comprises an upper rear clamping plate and a lower rear clamping plate. In a test, a sample for a plate compression performance test is cut and processed, the processed sample is tightly clamped in the U shaped groove of the rear clamping plate by the front clamping plate, then the sample is connected to an electronic universal testing machine, the test is stopped, when the downward displacement of the pressing head of the testing machine reaches 2 mm, and the compression performance test is finished. The method is smart, the consistency between the sample and the clamp is strong, the structure is rotationally symmetric, the processing is convenient and quick, the test method can be used to test the compression performance of a thin-wall plate at different temperatures, large deformation is realized, and the deformation is stable and uniform.