The invention relates to a movable positioning pin which comprises a base 1, a nut 2, a pressure spring 3, a positioning pin body 5 and a bush 4. A stepped through hole is formed in the base 1. A step is disposed on the through hole. The positioning pin body 5 is mounted on the bush 4. The positioning pin 5 is sequentially provided with a positioning part 7, a mounting part 8, a protruding part 6 and a guide part 9. One end of the pressure spring is clamped at the protrusion 6, and the other end thereof is clamped at the nut 2. The diameter of the positioning part 7 is smaller than that of the mounting part 8. The movable positioning pin has the advantages that the design structure of the movable positioning pin fully considers factors such as assembling, adjusting and cleaning of the positioning pin structure, the continuous machining requirements of the positioning hole can be satisfied, accurate positioning and smooth avoidance can be achieved, hole remachining can be achieved, part disassembling can be avoided during machining, no independent parts exist, and safety of machining processes is guaranteed.