In order to realize the high precision 3D measurement for the objects with different color under different illumination, the phase composition, phase coding and global phase unwrapping methods are researched. First, three different frequency sinusoidal waveforms are selected to be projected to the object after 3~8 phase shift. The equivalent frequency is acquired by the phase composition. The phase coding according to the three different frequencies is performed based on the equivalent frequency. Through the global phase unwrapping method, the global phase can be acquired, further to compute the high precision 3D coordinate. The precision testing method and comparison between the proposed method and the Gray Code method are introduced at last. Experimental results indicate that the precision of the Gray Code method is 0.04 mm; and the precision of the proposed method is 0.02 mm. The proposed method is high precision and better than the Gray Code method because it can solve the problem of the objects under different illumination.