Abstract: Antimicrobial peptides, as natural preservatives, had a wide application prospect in the food industry due to their high efficiency, stability and safety. To determine the optimal fermentation condition for producing antifungal peptides from Lacticaseibacillus paracasei ALAC, this study took the antibacterial zone as the indicator, the effects of fermentation time, fermentation temperature, initial pH and inoculum volume on the production of antimicrobial peptides were studied by single factor experiments and the response surface optimization was performed using Box-Behnken design on three parameters that significantly affect fermentation time, inoculation amount, and initial pH. Results showed that, when the inoculum amount of 4%, initial pH of 7.0, and fermentation time of 24 h, under this condition, the antibacterial substances produced by fermentation had the best antibacterial activity, with a diameter of 17.33±0.17 mm, this result could provide a theoretical basis for the production of antimicrobial peptide powder and its application in food.