The invention discloses a paint brush achieving rapid part replacing. The paint brush comprises a handle, a mounting plate and a brush head; a stud is fixedly installed at one end of the handle, a threaded hole is formed in one end of the mounting plate, the stud is rotationally sleeved with the threaded hole, a clamping groove is formed in the other end of the mounting plate, one end of the brushhead is slidably clamped in the clamping groove, bristles are fixedly installed at the other end of the brush head, connecting grooves are formed in the two sides of the clamping groove, stop blocksare fixedly installed on the inner walls of the connecting grooves, and locking devices are fixedly installed on the two sides of the brush head and slidably clamped in the connecting grooves. The handle is fixedly connected with the mounting plate through the stud and the threaded hole, the brush head is clamped in the clamping groove, at the moment, the locking devices are clamped in the connecting grooves, then the brush head is clamped in the clamping groove, and the phenomenon that the brush head falls off is avoided; when any portions of the handle, the mounting plate and the brush headare damaged, the paint brush can be detached to replace the damaged parts through the stud, the threaded hole and the locking devices; therefore, the remaining parts of the paint brush are utilized repeatedly, resources are saved, and the cost is reduced.