Led filament welding mostly completed by adopting manual welding, low efficiency and high defective rate, to solve the problems of traditional LED filament welding, in this paper, a LED filament spot welding robot based on machine vision is designed. The robot can identify the lamp filament and lamp post on the production line instead of artificial, acquire the target image to process, extracting solder joint location information to complete the corresponding welding operation. The paper focus on the general structure of the robot, expounds the working principle of the robot vision system, makes intensive study on image segmentation algorithm, designed image acquisition, gray level transformation, two value transformation, edge detection and so on a series of image processing procedures. Finally, the simple 3D model of the production line and the robot body is established.