A method for fast diagnosing gastric cancer is proposed, by combining optical fiber Raman spectroscopy system matching the gastroscope with the ratios of the spectral integral energy. we complete the detecting of Raman spectra from 17 samples of normal gastric mucosa and 12 samples of gastric adenocarcinoma mucosa using the optical fiber Raman spectroscopy system (excitation wavelength of 785 nm light, power of 50 mW, the CCD tem-perature to 80 ℃, acquisition time 1 s). Then, the original Raman spectra were pretreated, through reducing the baseline and smoothing by fast Fourier transformation (FFT). Finally, according to the characters of Raman spectra, Raman characteristic peaks were analyzed. At the same time, we compared the ratio of integral energy of conti-nuous band (1500 cm-1~1700 cm-1) and non-continuous band (1100 cm-1~1200 cm-1). The results show that the in-tensity of Raman peak of gastric adenocarcinoma at 1002 cm-1、1073 cm-1、1450 cm-1、1655 cm-1 belonging to phenylalanine and proteins are higher than that of normal mucosal relatively. From continuous band (1500 cm-1~ 1700 cm-1) and non-continuous band (1100 cm-1~1200 cm-1), the ratios of the spectral integral energy of gastric adenocarcinoma were different with normal mucosa markedly(independent samples t test, P<0.05), and with the ra-tio of the integral energy for use as a diagnostic index, obtained the higher accuracy (97.5%~98.5%), sensitivity (91.7%) and specific degrees (100.0%).