The works aims to review the principle, characteristics and research progress of intelligent indicator for food freshness. The research status and application of freshness indicator with CO2, volatile nitrogen compounds, hydrogen sulfide, pH change and microbial metabolites as indicators of color change were summarized with reference to relevant literature. Freshness indicator has scientific, intuitive and convenient technical characteristics, and has unlimited potential in the future packaging market. At present, the freshness indicator industry needs to get out of the predicament of poor accuracy and stability and continue to make efforts in ensuring food safety, thus truly realizing the functionalization, intelligence and informatization of food packaging, ensuring the reliability and safety of the quality, and making the freshness indicator appear on the mass market as soon as possible.