Color encoded phase-stepping light projection method is a new and promising technique for 3D shape modeling However, the 3D model acquired is often smeared by large error. The main cause of the error is color coupling amongst the three primary colors RGB. In this paper, we first analyzed the color-coupling problem. It is found that there is a strong coupling between G and R element. The coupling between R and G are proportional to the phase interval between them and the overall intensity of image. Second, we proposed an adaptive phase stepping method to alleviate the color coupling errors efficiently and improve accuracy effectively. An algorithm corresponding to a specific paradigm with R-G-B phase step set to 0-45-180 is given and is applied to measure different objects. Experimental results demonstrate the effectiveness of the method.