The present disclosure discloses methods for high-yield fermentation of recombinant proline aminopeptidase and preparation of debittered rice peptide, belonging to the fields of fermentation technology, enzyme preparation and food additives. The present disclosure utilizes fermentation kinetic analysis to determine the high-yield fermentation method of proline aminopeptidase by recombinant Bacillus subtilis, and improve the yield of proline aminopeptidase to reach 174.8 U/mL. Proline aminopeptidase cooperates with alkaline protease and leucine aminopeptidase to hydrolyze rice protein. The free amino acid content is 27.3 times the unhydrolyzed free amino acid content, and the small peptide content below 180 Da in hydrolysate reaches 44.70%. The exposed N-terminal proline residue is fully hydrolyzed, and the free proline content is 1,064.3 times that of the unhydrolyzed free proline content, which increases the degree of rice protein hydrolysis. The method of the present disclosure has a good application prospect in the fields of foods and beverages and processing and utilization of food protein resources.