A method of digital coding of grating by using color strips is presented. White, red, green, blue and their complementary colors, black, cyan, magneta and yellow are used to code the grating based on the binary system. The white and the black stripes are used to represent 1 and 0 on the fourth bit, red and cyan to represent 1 and 0 on the third bit, the green and magenta to represent 1 and 0 on the second bit and the blue and yellow to represent 1 and 0 on the first bit of the binary system, respectively. There are 64 stripes in one period. The space period of the projection grating is large enough for measuring the surface profiles of normal objects. Since each strip has only one logical state, the system possesses good disturbance-resistance.