The nude mice which were injected with the human gastric cancer cells (SGC-7901) in their peritoneums were chosen as the animal models of gastric cancer peritoneal dissemination in our research. The laser-induced autofluorescence spectra of these mice which were in different tumor planting periods and the normal counterpart were taken in vivo during the simulated surgeries. The spectra of different tissue types were compared and classified by clustering analysis and discriminate analysis. The results indicate the intensities of reduced nicotinamide adenine dinucleotide (NADH) are gradually decreasing while the one of Protoporphyrin IX (PpIX) are increasing with the growing of the cancer cell. The distinguish of the normal group and the tumor groups with different growth times of cancer cells is quite obvious when the measure method of interclusters and cluster number were set to square euclidean distance and 3,respectively. The technology of laser-induced autofluores cence (LIAF) may help to increase the accuracy of distinguishing the carcinoma metastaticum during surgeries.