The work aims to study the effects of the added amount of mulberry anthocyanins (MA) on the physicochemical properties and functional activity of pueraria starch/chitosan composite films. A new type of edible pH indicating films was prepared by casting with pueraria starch and chitosan as film-forming substrates and MA as an indicator. The physical properties, oxidation resistance, pH indication and other properties of pueraria starch/chitosan composite films were determined, and the indicator film was used for pork preservation and freshness detection studies. The results showed that the formation of hydrogen bonds between MA and pueraria starch greatly improved the tensile strength of the composite film. The addition of MA resulted in a significant increase in thickness, opacity, tensile strength (TS), water vapor permeability (WVP), and a significant decrease in elongation at break (EAB). In addition, MA improved the oxidation resistance and pH sensitivity of the composite film. The DPPH radical scavenging rate of MA-4 reached a maximum value of 85.24%. When the composite film was applied to the pork freshness test, the MA-loaded composite film had better antimicrobial properties compared with the control group, which could produce a color change visible to the naked eye, with MA-3 showing the most sensitive color change. Composite films incorporating a certain amount of MA are able to improve their tensile strength, opacity, pH sensitivity, and antioxidant activity, and could be used to monitor pork freshness in real time and delay pork spoilage, providing a basis for further research on smart food packaging materials.