Abstract: White colors comprise approximately 3% of the total volume of CIELAB color space, but the relative importance of white materials is much larger than perhaps the small volumetric sector that represents white in the CIELAB color space. Numerous fiber materials contain yellowish impurities which are natural or formed in production. Such yellowish impurities significantly impair materials' whiteness. Hence, chemical bleaching and fluorescent whitening are often performed to improve materials' whiteness. In order to increase production effectiveness of white materials, researchers have developed whiteness indexes based on visual evaluation of white materials for instrumental measurement of whiteness. However, the instrumental measurement has been found to be not so accurate for whiteness evaluation, especially for measuring fluorescent whiteness. This paper mainly discussed the correlation between the instrumental measurement and the visually perception of fluorescent whitened textiles, and highlighted the possible factors affecting the instrumentally measured whiteness of fluorescent whitened textiles. A research project was proposed to optimize the correlation between the instrumental measurement and the visually perception of fluorescent whitened textiles and thus to improve the accuracy of the instrumentally measured whiteness of fluorescent whitened textiles. This paper provides new insight into the whiteness evaluation of fluorescent whitened textiles by enhancing the correlation between the instrumental measurement and the visually perception of fluorescent whitened textiles.