Objective: To establish a sensitive,specific and rapid enzyme linked immunosorbent assay（ELISA） method for the determination of anti-PD-1 monoclonal antibody（code: BGB-A317） in Cynomolgus monkey serum. Methods: A indirect ELISA method was established for quantitative analysis of BGB-A317. For the determination of the BGB-A317,the recombinant human PD-1 was coated on the solid phase carrier,and diluted serum samples were added,following by HRP labeled goat anti-human IgG as enzyme labeled antibody. TMB substrate was added for color development and the reaction was terminated by 2 mol·L^-1 of sulfuric acid. Finally, the absorbance of each well was measured by a microplate reader under 450/630 nm. The calibration curve was generated by the D_450/630nm value versus the concentration. Fit the calibration curves using a 5-parameter logistics algorithm to get the standard curve equation,and substitute the sample D_450/630nm to be tested into the equation to obtain the sample concentration to be tested. Results: An ELISA assay was developed and validated with the quantitative range of concentrations from 3 to 180 ng·mL^-1. Precision（within-plate and between plates） was within ±15% and the accuracy ranged from 75% to 125%. The blank Cynomolgus monkey serum,sample diluent and interfering monoclonal antibody had no effect on the concentration determination of BGB-A317 in Cynomolgus monkey serum,the precision of dilution linearity samples was less than 20%,and the accuracy ranged from 80% to 120%. The precision of parallelism samples was less than 20%. BGB-A317 in Cynomolgus monkey serum was stable after stored at room temperature for 4 hours,below -70 ℃ for 70 days and repeatedly frozen and thawed for 3 times,and the sample accuracy ranged from 80% to 120%. Conclusion: This method is highly sensitive,accurate, specific,and reproducible. It is proven to be feasible for the quantitative analysis of anti-PD-1 monoclonal antibody in Cynomolgus monkey serum.