Rice hydrolysate (RPH) was obtained by using trypsin, and then the nanoparticles of RPH-daidzein composite were fabricated for daidzein delivering. The effects of hydrolysis degree (DH), RPH concentration and daidzein concentration on the characteristic of the composite nanoparticles were investigated by single factor experiments. When the RPH-daidzein composite nanoparticles was prepared under the conditions of a DH of 12%, an enzymatic hydrolysate concentration of 7.5 mg/mL and a daidzein concentration of 0.75 mg/mL, the particle size, polydispersity index and Zeta-potential of the nanoparticles were 449.71 nm, 0.23 and -22.30 mV, respectively. The encapsulation efficiency of daidzein was 60.07%, and the loading amount was 6.01 mg/g. The composite nanoparticles were verified to have high stability, and the feasibility of using RPH to fabricate nanocarriers loading daidzein was confirmed. Using RPH to prepare a nano-delivery system not only enriches the protein types of protein-based nano-transport carriers, but also provides a theoretical reference for the high-value utilization of rice protein resources.