In order to avoid the nonlinear problem caused by multilevel gray valu e coding,and to improve the speed and the adaptability of the measurement,a new method of binary encoding is proposed to get the stair phase.First of all,using the traditional N-step phase s hift method,a number of sinusoidal grating fringes are projected onto the surface of the object to be measured,and then a number of bi nary coding fringes are projected onto the tested objects.After the wrapped phase is obtained through a four-ste p phase-shifting method,by using the stair phase got from the binary encoded fringe demodulation,the grating peri od orders are determined,the wrapped phase is unwrapped according to the periodic orders,and eventually the absolute phase is obtained. The method of using binary fringes to encode stair phase has overcome the the n onlinear problem.Experimental results show that with a standard of the number of single channel image projection,and under the same con ditions,the measurement speed is enhanced by 12.5% compared with that of existing method.The method is efficie nt for the 3D shape measurement of objects.