Visible and near-infrared reflectance spectroscopy(Vis/NIRS) technique was applied in the early detection of grey mold(cinerea) on eggplant leaves while the symptom had not appeared.Chemometrics was used to build the early detection model.In order to decrease the amount of calculation and improving the accuracy,principle component analysis(PCA) was executed to reduce numerous wavebands into several principle components(PCs) as input variables of BPNNS while the PCs plot of three primary PCs was failed.The performance of the BPNNS model is good with 100% recognition rate and 88% correct rate.Thus,it is concluded that the spectra technology is an available one for the early detection of grey mold on eggplant leaves while the symptom has not appeared and it provides a new method for the early detection of grey mold.