Abstract: 【Objective】 Process optimization of tomato and carrot mixed juice prepared by compound enzyme,Optimum process conditions are obtained.Which can provide theoretical basis for the production process of mixed juice. 【Methods】 With tomato and carrot as raw materials, compound enzyme (cellulase and pectinase) is used to prepare fruit juice, The effects of 4 single factors: enzyme ratio, enzyme addition, enzymolysis time and enzymolysis temperature on the quality of mixed juice were explored. On this basis, Design-Expert was used to optimize the response surface of 4 factors and 3 levels, and a multiple regression model was established and analyzed by analysis of variance. 【Results】 When the compound enzyme was 1∶2, the enzyme addition amount was 24.5 g/L, the enzymolysis temperature was 45℃, and the enzymolysis time was 63.00 min, the juice yield and light transmittance of the mixed juice were 84.86% and 95.11%, respectively. In addition, the total phenol content of enzymatically hydrolyzed juice was higher than that of non-enzymatically hydrolyzed juice.(125.41 μg GAE/mL). 【Conclusion】 The compound enzyme method can significantly improve the juice yield, light transmittance and total phenol content of tomato and carrot mixed juice.