Clubroot,caused by Plasmodiophora brassicae,is considered the most devastating soilborne disease in Brassica crops.It has emerged as a serious disease threatening the cruciferous crop production industry in China.Nowadays,the detection techniques for P.brassicae are laborious,time-consuming and low sensitivity.Rapid and effective detection methods are needed.The objective of this study is to develop a Fourier transform infrared spectrometer(FTIR) technique for detection of P.brassicae effectively and accurately.FTIR and Real-time PCR techniques were applied in quantitative detection of P.brassicae.Chinese cabbages were inoculated with P.brassicae.By analyzing the FTIR spectra of P.brassicae,infected clubroots and healthy roots,three specific bands 1 105,1 145 and 1 228 cm-1 were selected.According to the correlation between the peak areas at these sensitive bands and Real-time PCR Ct value,quantitative evaluation model of P.brassicae was established based on FTIR y=34.17+12.24x1－9.81x2－6.05x3,r=0.98(p<0.05).To validate accuracy of the model,10 clubroot samples were selected randomly from field,and detected by FTIR spectrum model,the results showed that the average error is 1.60%.This demonstrated that the FTIR technology is an available one for the quantitative detection of P.brassicae in clubroot,and it provides a new method for quantitative and quickly detection of Chinese cabbage clubroot.