Gear detection technology is one of the effective means of production and quality control ability to test gear.With the constant improvement of gear accuracy requirement in recent years, non-contact measurement method for gear parameters is more and more applied to the actual production and quality control link. A method for measuring the tooth profile of gear by machine vision was presented.In this measurement system, contour fitting method was used to measure the gear tooth profile basic parameters; with event structure program, the gear tooth shape parameters measurement system based on vision was completed. With USB camera and a backlight source for lighting, connecting to the computer via the USB interface,using LabVIEW graphical programming platform IMAQ module, the collected gear image was processed.Also the system measurement error analysis module was joined to real time calculate and display the error of measurement.The experimental results show that this system runs stably, has good repeatability and high measurement precision.