Abstract: A novel multifunctional monocular visual sensor based on combined laser structured lights is proposed and designed; its research and development ideas and structural design process are detailed. The proposed visual sensor can realize multi-functions of detection such as the cross-sectional sizes of welding groove, the height, space position and posture of welding torch by using monocular vision and single image processing. The calibration of the sensor makes full use of its intrinsic parameters, and there is no need to re-calibrate the sensor when the position and posture of welding torch changes, which effectively improves the adaptability of the sensor in the welding process of complex structural workpiece and welding trajectory. With the use of combined laser structured lights, the problem of information loss in the depth direction existing in usual monocular visual sensor is solved effectively. Finally, the corresponding detection algorithms for the cross-sectional sizes of the V-type groove and the height of welding torch are derived, and the experiments are carried out to verify them. The experimental results show that the maximum relative detection error is not more than 2.1%.