In order to prolong the shelf life of the product and intelligently monitor its quality changes, the freshness indicator packaging film was prepared by casting method using acetylation and phosphorylation dual-modified cassava starch as raw material and anthocyanin as color indicator. An orthogonal experiment was conducted to investigate the interaction effects of cassava starch type, cassava starch mass concentration, glycerin content and anthocyanin concentrate content on the physical, mechanical and water vapor barrier properties of packaging films. Finally, the color intelligent response characteristics of the optimal film in fish fillets packaging were analyzed. The results showed that when the mass concentration of acetylated distarch phosphate was 40 g/L, the glycerol content was 30% (based on the gravity of cassava starch, the same below), and the anthocyanin concentrate content was 30% (based on the gravity of cassava starch, the same below), the comprehensive performance of the prepared packaging film (S1 film) was optimal. And the transparency, hydrophobicity, water vapor barrier capacity and tensile strength of S1 films were increased by 36.18%, 72.38%, 40.00% and 353.37%, respectively, compared with the natural cassava starch films. The S1 film was pink, purple and yellow-green in acidic, neutral and alkaline environments, respectively, and was sensitive to the ammonia gas. The color change of S1 films could indicate the freshness level of fish fillets. Purple was considered “fresh”, gray was considered “semi-fresh”, and green was considered “deteriorated”.