Objective To evaluate the pharmacokinetic parameters of human coagulation factor Ⅸ (FⅨ) after single intravenous injection in patients with hemophilia B, and to preliminary analyze the clinical implications. Methods In a single-arm, open-label, multicenter clinical trial, 13 male patients aged 25-64 years with hemophilia B received a single intravenous injection of FⅨ at 50 international unit (IU)/kg under non hemorrhagic conditions. Blood samples were collected at 2 h before injection, 15 min, 30 min, and 1, 3, 9, 24, 48, 72, 96 h post-injection to measure FⅨ activity. The FⅨ pharmacokinetic parameters were calculated by non-compartment model. In addition, FⅨ inhibitors in patients were measured 30,90 d after injection.Results The plasma FⅨ concentrations peaked at 51.5-69.3 IU/dL in all patients after single intravenous injection of FⅨ for 15 min-1 h. The baseline-corrected pharmacokinetic parameters (±s) of FⅨ were below: peak time (0.37±0.22) h, elimination half-life (29.732±4.576) h, peak concentration (58.3±5.3) IU/dL, clearance (0.028±0.006) dL/kgh, area under the plasma drug concentration time curve (zero time to last time point) (1 626.189±285.365) %h, and incremental recovery rate (1.166±0.106) IUdL-1/IUkg-1. At 1 h post-injection, FⅨ activities were 40%-60% in all 13 patients, which maintained 40%-60% in 12 patients 3 h post-injection, and were still 40%-60% in 8 patients 9 h post-injection. No FⅨ inhibitors were detected in all 13 patients. Conclusion After single intravenous injection of FⅨ at 50 IU/kg in patients with hemophilia B, the major pharmacokinetic parameters, such as elimination half-life and clearance, indicate effective maintainence of blood concentrations in vivo, which can be used for further clinical studies on the efficacy of replacement therapy.