A microscopic image vision imaging system composed of a telecentric lens, a ring LED light source, an industrial digital camera and a stepping motion controller is designed to be used for LD coupling lens focal spot detection. The diameter and center of the outer circle of the module, and the center and position of the LD laser focal spot emitted by the LD coupling lens are detected. The focal length of the coupling lens and the eccentricity of the LD are obtained to provide precise positioning for subsequent coupling with the optical fiber. The experimental data show that the standard deviation of the eccentricity measurement of the system is less than 5 μm, and the standard deviation of the focal length measurement is less than ±0.1 mm. The relative position relationship between the focused spot and the base circle center can be accurately obtained. The experimental results are accurate and the measurement efficiency is high.