The work aims to clarify the effect of cooking treatment on the content of polyphenols and antioxidant activity in mung beans, and obtain the optimal extraction conditions and cooking process of mung bean polyphenols to maintain a high polyphenol content and antioxidant activity during the cooking process of mung bean, thus providing strong data support for the development and utilization of mung beans. In this experiment, with the mung bean produced in Shanxi as the raw material, the polyphenols of mung bean were extracted by ultrasonic-microwave (U-M) synergistic extraction method, and the traditional cooking method was used for cooking. The polyphenol content was quantitatively detected by the Folin detection method. The single factor and orthogonal tests were carried out with polyphenol content as the index to obtain the best extraction conditions. On the basis of it, the best cooking process was discussed, and the cooked mung beans were subjected to sensory evaluation analysis. The DPPH free radical scavenging and total antioxidant kit tests were used to analyze the antioxidant capacity of mung bean polyphenol extracts before and after cooking. The test results showed that, when the optimal extraction parameters were as follows: U-M treatment time was 30 min, the treatment temperature was 40 ℃, the extraction solid-liquid ratio was 1︰15 (g/mL) and the ethanol extract concentration was 60%, the polyphenol content was 3.14 mg/g. When the cooking power was 400 W, the cooking solid-liquid ratio was 1︰25 (g/mL), and the cooking time was 30 min, they were the best parameters of the cooking process. Its polyphenol content was 2.45 mg/g, and the sensory evaluation score was 83 points. The mung bean polyphenols' ability to remove DPPH was 69.54% of the control group and 56.30% of the cooking treatment group, and the total antioxidant capacity was 29.13 U/mL of the control group and 23.57 U/mL of the cooking treatment group, indicating strong anti-oxidation ability, and showing a dose-effect relationship. This experiment preliminarily clarifies the effect of cooking treatment on the content of polyphenols and their antioxidant activity in mung beans. The polyphenol content in cooked mung bean is low and its antioxidant capacity is weak. On the basis of ensuring the flavor, the cooking process is optimized to provide a scientific reference for the rational use of mung bean polyphenols.