The shape size of the nozzle in the water-jet loom plays an important role in the operation of the loom. In order to efficiently detect the shape and size parameters of the loom nozzle with high precision, a nozzle shape size detection system based on machine vision is designed. In this system, the rotation of the nozzle is controlled by stepper motor, the nozzle image is collected from multiple angles by CCD camera, the outer contour edge of the nozzle is obtained by sub-pixel edge detection method, and then the edge is fitted in a straight line. finally, the diameter, taper and tilt angle of the nozzle are calculated. The experimental results show that the relative error of diameter measurement of the system is less than 1%, and the angle measurement error is less than 2′. Multi-angle measurement can improve the measurement accuracy of taper and inclination angle. The system has high detection accuracy and can meet the requirements of practical production and application.