Objective To develop a near infrared diffuse reflectance spectroscopy with partial least square fitting(NIR-PLS) for nondestructive quantitative analysis of Vitamin C in Vitamin C Tablets.Methods A mathematical calibration model(110 samples) of NIR was proposed using the second derivative spectrum in the wavelength range of 10 000-4000 cm-1.This model was applied to predict the validation set and detect the marked concentration of Vitamin C in Vitamin C Tablets.Results The correlation coefficient(r) of the prediction value and the actual value in calibration set was 0.996 9,the root mean standard error of calibration(RMSEC) was 1.30.The root mean standard error of prediction(RMSEP) was 0.656 from the cross-validation.The average recovery of the prediction set was 97.24%(RSD = 4.89%,n = 10).Conclusion The established method is a rapid and simple way with good accuracy.The method can be applied in rapid qualitative and quantitative analysis of drugs.