The invention relates to a high-temperature compression test clamp. The clamp comprises an upper compression body and a lower compression body, wherein the upper compression body and the lower compression body are U-shaped components; the U-shaped opening ends of the upper and lower compression bodies are arranged in opposite directions, and are in crossed butt joint to form a compression cavity for accommodating a sample; and the sample is fixed in the compression cavity along the compressing direction. According to the high-temperature compression test clamp, the upper compression body and the lower compression body which are in crossed butt joint are adopted, and the tensile force of the upper and lower compression bodies is transformed into pressure for the sample, so that a compression performance test is carried out by a tensile mode. The high-temperature compression test clamp is simple in operation, does not require strict alignment operation, and has the characteristics of simple structure, convenience in use and relatively high measurement accuracy.