OBJECTIVE： To develop a method for rapid determination of water content in Cinnamomum cassia. METHODS： The moisture of sample was determined by toluene method （as reference value）. IFRS-PLS was used to establish quantitative correction model of moisture in sample. According to moisture determination of sample， 80 batches of samples were collected， and constant offset elimination method was used to pretreat spectrum. The optimal spectrum range for moisture determination of medicinal sample were 7 502.2-6 896.6 cm－1 and 5 600.6-4 998.9 cm－1. RESULTS： The internal cross validation decision coefficient （R2） of moisture quantitative correction model was 0.974 9， and the root mean square error of cross validation （RMSECV） was 0.404. R2 of model external validation was 0.940 4， and the predicted root mean square error was 0.306. CONCLUSIONS： The method is rapid， accurate， simple and free from pollution. It can be used for rapid determination of moisture in C. cassia.