The invention relates to a disassembling device for an oil well pipe protective cap, which is used for disassembling the oil well pipe protective cap and comprises a bracket (1). A motor (2) is arranged at one end of the bracket (1), and two movable guide rails (3) are arranged in parallel at the other end; a rotating wheel (21) is arranged at the output end of the motor (2), a plurality of positioning blocks (22) are arranged on the rotating wheel (21), a movable plate (31) is inserted between the two movable guide rails (3), and two positioning pipes (32) are fixed at one end of the movable plate (31) far from the motor (2); a positioning clamping groove (35) is arranged on the inner wall of a positioning ring (33), a guide pipe (34) is arranged at the bottom part of the positioning ring (33), and a pin shaft (36) is inserted into the positioning pipes (32) and the guide pipe (34) at the same time. The disassembling device for the oil well pipe protective cap can increase the disassembling efficiency.