As the defects seriously affect the quality grade of float glass,the on-line defect detection technology is important for improving the quality of glass products.This paper presents an on-line defects detection method for float glass based on digital fringe projection profilometry.Firstly,the digital projector and the high-speed camer a are placed on the upper side of glass sheet which is moving on the production line,the digital projector projects fringe through t he glass sheet and images it on the background,and the camera captures the fringe image which is modulated by glass surface.The glas s defects would change the phase distribution of fringe image,then the image processing computer extracts and reconstructs t he phase information of the collected defect image which is out of shape,the out of plane displac ement can be obtained by mathematical relationship,and finally the diopter of defects glass can be calculated.This method has been appl ied to the float glass defect detection filed,and can successfully detect the optical distortion defects which are difficulty for other traditiona l methods.The experiment results show that the digital fringe projection method can detect the smaller optical distortion defects,and the detection accuracy can reach 0.1mm.