Abstract: It is of great significance to prepare indicator labels that can intuitively express the freshness of fruits and vegetables with the development of new fresh e-commerce forms and the improvement of the functional requirements of fresh-keeping packaging. In this study, the mixture of methyl red and bromothymol blue（3∶2） was prepared as an indicator, combined with polyethylene glycol（PEG）-6000 as plasticizer and methyl cellulose as film forming matrix,which was used to prepare freshness indicator labels for fruits and vegetables based on pH changes, aiming to investigate the freshness indicating effects on strawberries and lettuces packaging. The results showed that the volume fractions of CO₂in fruits and vegetables packaging were increased continuously, and the pH values were continuously descended with the prolongation of storage time. The color of four prepared indicator labels all changed along with pH values, and label 3（50 mL/L methyl red-bromothymol blue mixed indicator） and label 4（70 mL/L methyl red-bromothymol blue mixed indicator） presented the widest range of color variations, covering 4 color systems of green, chartreuse, orange and red. Among them, the color difference values △E of label 3 had the highest fit with the sensory scores of freshness of fruits and vegetables（R~2=0.834 6）. Therefore, 50 mL/L methyl red-bromothymol blue（3∶2） freshness indicator label was determined as the best indicator.