A visual recognition based method for projecting patterned light includes: projecting a calibration image onto a projection screen by a projection module; capturing the calibration image by an image-capturing module to obtain a calibration information between the projection module and the image-capturing module; capturing an object by the image-capturing module to obtain a to-be-recognized image of the object; detecting the object in the to-be-recognized image and acquiring a plurality of feature points associated with a plurality of feature areas of the object in the to-be-recognized image; retrieving a plurality of target feature points corresponding to a target object from the feature points; obtaining a projection coordinate of the target feature points\ according to the calibration information and providing the projection coordinate to the projection module; and projecting a projection pattern with shape corresponding to the target object onto the object by the projection module according to the projection coordinate.