The present invention provides a mechanism for rapid measurement of a cartridge receiver outer wall radial difference and an application method thereof. A movable measurement portion employs a linearbearing installed in a measuring body to achieve axial and circumferential motion. The rotation and the radial sliding of the measurement portion in the measuring body solve the stroke problem of measurement of an inner cavity. A fixed measuring rod provided with a sliding measuring rod performs stable and barrier-free sliding on the linear bearing, so that it is ensured that the sliding measuringrod and the fixed measuring rod are located in the same line and unstable factors caused by man-made force application measurement can be eliminated. The measurement effect is high and the measurement data is sensitive, the measurement for the dimensions of the inner portion of the cavity is convenient and rapid, the production efficiency is improved, the application effect is good. The mechanismfor rapid measurement of the cartridge receiver outer wall radial difference and the application method thereof have practical application values, can effectively avoid a problem of interference on measurement caused by parts, and can accurately and rapidly measure the cartridge receiver outer wall radial difference. The measurement method is simple and convenient and rapid in operation. Meter setting is performed on a standard piece when in measurement, detection is performed on a cartridge receiver part to be measured, and the measurement mode is relative measurement to improve the measurement precision and to improve the production efficiency.