Abstract: In order to study the immune adjuvant effect of solid lipid nanoparticles through surface adsorption of antigen proteins, the experiment was conducted to prepare solid lipid nanoparticle suspensions（SLN1 and SLN2） by hot-melt phacoemulsification, and the mean diameter（MD）,polydispersity index（PDI）,and zeta potential（ZP） of the nanoparticles were measured with a laser nanoparticle sizer. Using BSA protein as the marker antigen, 36 ICR female mice were randomly divided into 6 groups, namely BSA solution group（500 μg/mL BSA solution 1 mL）,BSA-SLN1 group（BSA-SLN1 950 μL+10 mg/mL BSA 50 μL）,BSA-SLN2 group（BSA-SLN2 950 μL+10 mg/mL BSA 50 μL）,BSA-CFA group（1 mg/mL BSA solution 500 μL+CFA 500 μL）,blank SLN group（SLN suspension without BSA 1 mL） and normal saline negative control group（sterilized normal saline 1 mL）. Mice in each group were immunized by injecting 100 μL of the corresponding solution into the leg muscles; blood was collected at 2,4,and 6 weeks after immunization, and the serum antibody titer was detected by indirect ELISA. The results showed that the prepared solid lipid nanoparticle suspension was milky white in appearance, tasteless, and had no precipitation. Observed by the optical microscope, the size was relatively uniform and the dispersion was good. Compared with the SLN2 suspension, the MD,PDI and ZP of the SLN1 suspension were significantly different（P＜0.05）. The antibody titer of the BSA-SLN group was about 14 lb, which was significantly higher than the BSA solution group（10 lb, P＜0.05）,but significantly lower than the BSA-CFA group（18 lb, P＜0.05）,while the blank SLN group had the same test results as the negative control group, which were negative. In the 6 th week, the antibody titer of the BSA solution group was greatly reduced, while the BSA-SLN group and BSA-CFA group continued to maintain the original level. Comparing the adjuvant effects of nanoparticles of different particle sizes, the results showed that SLN1（237±2 nm） and SLN2（95±5 nm） of solid lipid nanoparticles had very similar adjuvant effects, and there was no significant difference in antibody titer between SLN1 and SLN2（P＞0.05）. The results suggested that SLN can significantly improve the immune response by adsorbing antigen proteins, and has a good adjuvant effect.