<p><b>OBJECTIVE</b>To screen and identify the serum specific protein markers of patients with gastric cancer by proteomics technology, and to provide more comprehensive serum protein fingerprint model for the early diagnosis of gastric cancer.</p><p><b>METHODS</b>Preoperative and postoperative blood samples were collected from 60 gastric cancer patients. Mass spectrometry (SELDI-TOF-MS) technology was used to detect and screen serum specific proteins in gastric cancer patients(preoperative group, postoperative group, metastasis group), and the result was compared with normal control group. Gel electrophoresis(TRICINE SDS-OAGE) technology was applied in the separation and purification for those different protein. Matrix assisted laser desorption ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF) technology was used in the identification for the proteins following separation and purification.</p><p><b>RESULT</b>Mass spectrometry data of preoperative group and normal group resulted in 15 specific m/z peak(P<0.01). SVM screened by a combination of the highest index model Youden get m/z peak at 6 449.1 protein markers. The protein expression of preoperative group was significantly higher than that of normal group(2 299.3±2 029.3 vs. 509.5±168.3, P<0.01). Mass spectrometry data of preoperative group and postoperative group resulted in 6 specific m/z peak(P<0.01). SVM screened by a combination of the highest Youden index model indentified get m/z peak at 6 449.2 protein markers. The protein expression of preoperative group was significantly higher than that of postoperative group(1 247.9±685.0 vs. 476.5±157.8, P<0.01). Mass spectrometry data of preoperative group and metastasis group resulted in 12 specific m/z peak (P<0.01). SVM screened by a combination of the highest Youden index model indentified get m/z peak at 6 448.9 protein markers. The protein expression of metastasis group was higher than that of preoperative group(1 506.9±1 036.5 vs. 649.7±621.0). MALDI-TOF/TOF identified that the protein with m/z peak at 6 449 was Apo CIII(.</p><p><b>CONCLUSION</b>Apo CIII( may be the specific serum protein marker of gastric cancer, which may provide a more comprehensive serum protein fingerprint model for the early diagnosis of gastric cancer and a new way for further research.</p>