The effects of different factors on the preparation of gelatin/sodium alginate composite gel were studied through the viscosity, dehydration rate and breaking strength of the gel at different ratios. The effects of glycerol on the water retention performance of the gel were analyzed by the rmogravimetry, infrared spectroscopy and differential thermal scanning. A composite gel with stable morphology was prepared, which can be used as an enzymatic time-temperature indicator. Finally, when the concentration of sodium alginate was 3 wt.%, the concentration of gelatin was 8 wt.% and the concentration of calcium chloride was 3 wt.%, the performance was the best, and the breaking strength could reach 571 kPa. The optimum concentration of glycerol was 30 wt.%, and the gel could keep 76% of the gel weight for 7 days at 4 ℃ and 70% humidity. Glycerol-rich gelatin/sodium alginate composite gel is stable in shape and able to temperature and time-related color changes under the action of glucoamylase, which proves that the gel can be applied to enzyme-type time and temperature indicators.