The gastric cancer is the second most frequently diagnosed cancer and the third leading cause of cancer death in China.80%-90% patients were detected at middle and later stage.The five-year survival rate for advanced gastric cancer patients is less than 10% due to the shortage of effective treatment method.The five-year survival rate for early gastric cancer patients is beyond 90%.The reason for poor diagnosis and treatment is that current methods do not achieve the diagnosis of early gastric cancer.Endoscopy with biopsy is still the main method for confirming gastric cancer.But it is limited to identify early gastric cancer and it leads to the low diagnostic rate of early gastric cancer.