Fused Deposition Modeling (FDM) is simple and cost-effective. While, there are no monitoring system to detect defects during the manufacturing process. In this paper, the quality of FDM is studied using the technology of the Machine Vision (MV) and Profile Control Chart. Firstly, the picture of each layer during the manufacturing process is caught with a camera. Secondly, the contours of these pictures are extracted with image processing methods. Finally, the profile errors of each layer are calculated and the data is analyzed with the methods of profile control and the control status is acquired. It can be concluded that all defects in counter profile can be successfully detected though this method.