In this paper, for evaluating the 3-D roughness of the additive manufacturing surfaces, we constructed a 3-D reconstruction system of structured light scanner. By calibrating the system, the center line of structured light is extracted online to reconstruct the profile of additive manufacturing and realize data registration. A dynamic texture coarseness algorithm is proposed, which combines 3-D data with 2-D Gaussian filtering and texture coarseness characteristics to transform 3-D roughness into visual image texture coarseness. The algorithm is applied to evaluate 3-D weld roughness with low delay. The validity of the algorithm is verified by roughness comparison specimens and the actual material adding experiment. The result of roughness is reliable and conforms to the evaluation standard of weld quality. At the same time, the position of structured light is optimized in the process of on-line detection, which reduces the complexity of extracting contour centerline and ensures the low delay characteristic of roughness calculation. INDEX TERMS 3-D reconstruction, dynamic texture coarseness, 3-D roughness of additive manufacturing.