In order to find the proper color space for promoting robustness against print-and-scan，the watermarks extracted from watermarked image embedded into CMYK and RGB color space were compared. Experiments showed that the watermark embedded into one channel diffused to other channels and reduced the quality of extracted watermark. The watermark extracted from watermarked image embedded into CMYK color space had higher quality than RGB space, which indicated that the transformation of CMYK→RGB→CMYK led to less damage for extracted watermark than in the transformation of RGB→CMYK→RGB. The future research on anti-counterfeiting print should mainly be focused on the embedded watermark CMYK color space.