Abstract: To better meet the demand for high-precision and rapid measurement of external thread parameters, a measurement scheme based on a pair of linear laser sensors is proposed. Through the Eye To Hand calibration to establish the spatial transform matrix between the color CCD camera and the robotic arm, the motion of the measurement unit driven by an image-guided robotic arm is achieved. The calibration of the plain plug gauge is realized by controlling the position of the robotic arm and the real-time feedback of the linear laser sensor’s data. The linear laser sensors collect the thread profile data, fit the major and minor diameter profiles with the least squares method, acquire the pitch diameter’s line with iterative method, and calculate the external parameters of major diameter, minor diameter, pitch diameter and pitch. After analyzation the source of errors from the measurement system, the expanded uncertainty of the measurement of pitch diameter is calculated to be U = 6.3 μm. The results of the comparative experiments demonstrate that this measurement system can realize the high-precision and high-speed measurement of external thread parameters.