The paper aims to prepare a gelatinous rice freshness indicator material with natural polymer materials as the main raw material, and explore its effect on rice freshness. Using sodium alginate, calcium carbonate and other auxiliaries as raw materials, methyl red and bromothymol blue as indicators, rice freshness indicator material were prepared by in-situ release method. Through the detection of properties and swelling properties of materials, the optimal ratio of sodium alginate/calcium carbonate was 2 : 1, and the optimal additive amount of gluconolactone was 0.156 g. Through the identification and detection of fatty acids in rice by the indicator material, and the optimal volume ratio of methyl red and bromothymol blue was 7.5 :1, and the optimal additive amount of the total volume of the composite indicator was 13%. The sodium alginate-based rice freshness indicator hydrogecan be applied to the freshness detection of rice.