The invention discloses a corn juice and a preparation method thereof. Corn is subjected to microwave blanching after precooling, then xanthan gum, sodium alginate and konjac gum compound gum are added, the ultra-high temperature instant sterilization conditions are combined, the vacuum rapid precooling cooling technology of sweet corn improves the taste of the sweet corn, through the microwave blanching technology of sweet corn grain and optimization ultra-high temperature instant sterilization, the content of nutrients and antioxidants in the corn juice is increased, the content of carotenoids is increased, volatile flavor components are advantageously increased, such as alcohols substances, aldehydes substances, esters substances and terpenes compounds, and the taste and texture of thesweet corn juice are improved.