To further expand the application of marine fish protein on food products, the enzymatic modification of blue round scads (Decapterus maruadsi) isolated protein performed to obtain blue round scads protein isolate hydrolysate (BPIH) with good solubility. The inhibitory effects of BPIH on short-term retrogradation of rice starch (RS) was investigated. The enzymatic modification process was optimized by response surface methodology, and was added to RS with different contents of 3%, 6% and 9% (w/w). The measurements of coagulability, dynamic viscoelasticity, and thermal properties and microstructure of RS were carried out to evaluate the anti-retrogradation activities of BPIH. The results showed that the optimal conditions determined by response surface methodology were: enzyme bottom ratio of 5000:1 (U/g), enzymatic digestion time of 3 h, feed-to-liquid ratio of 1:3.81, enzymatic digestion temperature of 46.36 ℃, and enzymatic pH of 6.30. The actual value of nitrogen solubility index (NSI) was 85.41±0.82%, which was close to the predicted value of 86.37%. The degree of BPIH hydrolysis reached 21.62% under these enzymatic conditions. The peptides less than 1000 Da in BPIH accounted for 79.94%, which were mainly small oligopeptides. The addition of BPIH attenuated the coagulation phenomenon of RS, reduced the energy storage modulus (G") of RS during storage at 4 ℃, and significantly reduced the peak temperature (Tp) and enthalpy (ΔHr) of RS after aging (P<0.05); the rice starch added with BPIH had larger pores in the microstructure after aging, which enhanced the ability of starch to retain internal water after pasting. The above results suggest that BPIH can inhibit the formation of gel network and microcrystalline structure of RS during storage at 4 ℃, and may also limit the aggregation between starch molecules and inhibit or delay the short-term aging of RS. This study provides a theoretical reference for the application of the enzymatic digest of blue round scads isolated proteins in food protein ingredients.