An embedded angle visual inspection system for line structured light was established based on DM642 to detect the angle of the line structured light in real-time accurately. Firstly, a device using the CCD as its image sensor was fixed on a datum plane, and the other one using a line structured laser as its light source was fixed on the plane to be measured. The image of the line structure laser on a screen was acquired by the CCD and its angular position value was obtained by on-line processing of DM642.The angle between the datum plane and the measured plane could be gotten through calibration of the angular position value. Then, the angle α between CCD surface and projection screen surface was proved to be the dominant error source by an error analysis. For compensating the error, a mathematical model was established. On the basis of the model, a calibration method was used as follows: the circular grating was used to control the laser generator to rotate accurately three angular displacements, and the angle value of α and its direction were calculated according to the angular displacement value and the corresponding image detection, then the detection error brought by the angle could be compensated. The experimental results show that the angle error is reduced to 0.595% from 22.522% after compensation when α is 0.331 97° and the measuring uncertainty of the system is 0.051 44°.