Objective:To determine rapidly the content of water-extract in Salvia miltiorrhiza by near-infrared spectroscopy and the chemometrics method. Method: A calibration model of near-infrared spectroscopy was built up for determination of the content of water-extract in S. miltiorrhiza by partial least squares (PLS) method. Result: The best spectral pretreatment method is MSC

the best spectral collection range is 7 038.39-4 418.78cm-1

and main fraction is 6

correlation coefficient of calibration cross validation (R2)was 0.984 3

root mean square error of cross validation (RMSECV) was 0.857

and external prediction deviation RMSEP of 11 samples was 0.787.Predicted the average recovery was 100.03%. Conclusion: It was feasible to determine the water-extract content in S. miltiorrhiza. This method is fast and simple with consequence accuracy

which should be applied more extensively in traditional Chinese medicine system.