A structured light projection optical system for obtaining 3D data of an object surface includes a structured light projection optical part configured to project a plurality of patterns onto an object or a screen, and an imaging optical part configured to obtain 3D data by photographing the patterns being projected from the structured light projection optical part. The structured light projection optical part includes a plurality of light sources, and a plurality of pattern masks. As the plurality of light sources are turned on and off, the pattern mask matches any one of the plurality of light sources illuminating a light, and the plurality of patterns are projected on the object or the screen by the pattern mask. Accordingly, various patterns can be effectively projected, real-time measurement can be easily performed through a quick pattern change, and the accurate 3D data can be obtained.