Abstract: Objective: Modafinil acid concentrations of its metabolite in plasma was determined following a single oral dose of modafinil tablet in Chinese heathy volunters to prove the pharmacokinetic parameters in modafinil clinical trials. Methods: After 9 volunteers were taken respectively single-dose of 100mg, 200mg, 300mg modafinil tablet randomly by Latin method with 3 subjects in eath group,modafinil acid concentrations in plasma by HPLC method. The pharmacokinetic parameters were calculated by using 3P97program. Results: The main pharmacokinetic parameters of modafinil acid in 100mg、200mg、300mg groug were: Cmax 1.78±0.79mg·L^-1、3.17±1.27mg·L^-1 and 4.13±2.0.3mg·L^-1,T max 1.8h、3.1h and 2.8h,t 1/2β 2.35±1.97h、 2.45±1.07h and 1.95±1.18h,AUC 0-t 21.17±16.13mg·h·L^-1、25.74±7.74mg·h·L^-1 and 41.38±20.72mg·h·L^-1,CL 5.799±5.190 L·h^-1、7.800±3.420 L·h^-1 and 7.954±2.976 L·h^-1,modafinil tablet respectively. Conclusion: Cmax、AUC_0-t of modafinil acid was increased on the dosage of modafinil.There are no statistically singnificant between t _1/2β、T _max、CL and dosage of modafinil.