Aiming at the problem of the detection blind zone in the glue detection of a single line structured light sensor, a method using three line structured light sensors to measure the colloid is proposed for three-dimensional measurement. The three line structured lights surround the glue gun to form a closed triangle The light knife is projected vertically to the surface of the workpiece to be coated for real-time online detection. The camera is calibrated by Zhang Zhengyou′s calibration method, and the light plane is calibrated by the least squares plane fitting method. The measurement accuracy of the three line structured light sensors is analyzed by measuring standard blocks. The measurement results show that the measurement errors of the sensors are all less than 0.15 mm, which meets the measurement requirements. Finally, design experiments to measure the colloid in three dimensions and analyze the impact factor of measurement accuracy. Obtain the three-dimensional point cloud data of the colloid profile and perform three-dimensional reconstruction to obtain the three-dimensional contour map of the colloid cross section. Finally, the two parameters of the width and height of the colloid are extracted and combined with compare the results of manual testing. Experiments show that it is feasible to use this method to measure the geometric parameters of colloids.