Objective To investigate the properties of functional peptides in Hongjun Tofu.Methods Functional peptides were extracted from Hongjun Tofu by ultrasound-assisted water extraction. The crude peptide content was used as the evaluation index to investigate the effects of extraction time, pH, extraction temperature, and solid-liquid ratio on peptide extraction. Single-factor and orthogonal experiments were designed to optimize the extraction process, and the antioxidant activity of the obtained functional peptides was evaluated.Results The optimal extraction conditions were 35 minutes extraction time, 55 ℃ extraction temperature, pH 11, and a solid-liquid ratio of 1∶40 (g/mL). Under these conditions, the crude peptide content reached 114.07 mg/g, significantly higher than that under other conditions. Functional peptides from Hongjun Tofu exhibited antioxidant activity, with DPPH and ABTS radical scavenging rates of 69.46% and 79.18%, respectively, when extracted under optimal conditions.Conclusion Hongjun Tofu is an excellent source of food-derived functional peptides with antioxidant, nutritional, and medicinal health benefits, showing great potential for development and utilization.