Computer graphics and image processing software, as an auxiliary technology widely used in graphic design, can provide creativity and color display for graphic design. At the same time, image processing software can also improve the aesthetics and connotation of graphic design. This paper innovatively proposes a computer graphics and image processing reconstruction method for dynamic object model based on point cloud model. The method adopts the principle of watershed segmentation to segment the image and extract the contour of the watershed; and then uses the silhouette contour sequence modeling method to reconstruct the sparse point cloud model of the object. Finally, the experimental research proves that the image processing algorithm model proposed in this paper can quickly generate a flat model with compact description and appearance.