A fiber-optic Raman spectrum sensor system is used for the fast diagnosis of esophageal cancer during clinical endoscopic examination.The system contains a 785 nm exciting laser,a Raman fiber-optic probe with 7 large core fibers and a focus lens,and a highly sensitive spectrum meter.The Raman spectrum of the tissue could be obtained within 1 second by using such a system.A signal baseline removal and denoising technology is used to improve the signal quality.A novel signal feature extraction method for differentiating the normal and esophageal cancer tissues is proposed,based on the differences in half-height width (HHW) in 1200cm-1 to 1400cm-1 frequency band and the ratios of the spectral integral energy between 1600cm-1-1700cm-1 and 1500cm-1-1600 cm-1 band.It shows a high specificity and effectivity for the diagnosis of esophageal cancer.