The invention relates to an inner cavity cleaning clamp for a high-pressure oil pipe. A valve core is positioned in the center of a clamp body; a joint is sleeved at the upper end of the valve core; the lower part of the joint is in threaded connection with the clamp body; a sealing ring is sleeved on the waist part of valve core, and is positioned in a crack between the lower part of the joint and clamp body; a gap is formed between the lower part of the valve core and the clamp body; a bottom plate is arranged below the valve core, and is fixed with the clamp body; one end of a first compression spring is fixed on the bottom plate; the other end of the spring is pressed against the lower end of the valve core; a cavity is formed in the upper part of the valve core; the side wall of the valve core is provided with a valve core through hole for communicating cavities outside and inside the valve core; the valve core through hole is sealed with the sealing ring when valve core is jacked up by the first compression spring; the clamp body is provided with a pressure plate; two guide posts are arranged below the pressure plate; the lower ends of the guide posts are inserted into the clamp body; second compression springs are sleeved on the guide posts; and the upper end of the pressure plate is pressed by a compression cap. The inner cavity cleaning clamp has the advantages of capability of meeting the requirement of inner cavity cleaning of the high-pressure oil pipe, simple structure, easiness and convenience for assembling and disassembling a mold, safety and reliability.