The invention relates to a quick detector for an angle of a flow distribution window of a valve plate of a plunger pump, and mainly solves the technical problems, of a conventional detector, that detection time is long and the conventional detector is not applicable to key size detection of enterprise batch products. The technical scheme is that the quick detector for the angle of the flow distribution window of the valve plate of the plunger pump is composed of a base, pointers, stop pins, a full-round instrument, a vernier scale, a sliding bearing, a hinge pin and locating pins, wherein thelower part of the sliding bearing is arranged in a bearing hole formed in the middle of the base; a round ring of the first pointer and a round ring of the second pointer are mounted on a rotating shaft arranged at the center of the bottom surface of the full-round instrument in a sleeving manner; the first stop pin is arranged on the first pointer; the second stop pin is arranged on the second pointer; the rotating shaft arranged at the center of the bottom surface of the full-round instrument is mounted in a hole of the sliding bearing; one end of the vernier scale is mounted at the center of the top surface of the full-round instrument through the hinge pin; the vernier scale is positioned on the top surface of the full-round instrument; and the locating pins are mounted in locating pinholes formed in the top surface of the base.