The whiteness of Agaricus bisporus is an important index to evaluate its freshness and quality.In order to accurately evaluate the whiteness of Agaricus bisporus,a method based on machine image analysis was proposed.The imaging system of D65 standard light source is built,and the nonlinear whiteness calibration model is constructed.The conversion from RGB value to CIE-XYZ tristimulus value is realized,and then CIE Ganz whiteness formula is used to realize the accurate measurement of whiteness.The image system was calibrated by using 8 color cards with different gray levels in combination with a colorimeter,and the Agaricus bisporus with different whiteness grades were measured.The results showed that there was a high correlation between the results of image analysis and colorimeter (r=0.99),and the color difference ΔE*ab<2.For the four groups of Agaricus bisporus with different whiteness levels,the measurement results of image analysis were significantly different (P<0.01).At the same time,the whiteness value of Agaricus bisporus under different storage conditions was measured by image analysis.It was found that there was a significant correlation between the storage time and the whiteness value of Agaricus bisporus,which indicated that the whiteness value determined by image analysis can be used to quantitatively evaluate the freshness of Agaricus bisporus.