Background:The occurrence of gastric cancer is a gradual process with multiple factors and multiple steps. In addition to cytological and structural abnormalities,there are abnormal molecular expressions,which involve the activation of many oncogenes and the inactivation of tumor suppressor genes. Aims:To explore the expressions and significance of Ki-67,p53 and P504s in normal gastric mucosa,atrophic gastritis with intestinal metaplasia,low-grade intraepithelial neoplasia,high-grade intraepithelial neoplasia and early gastric cancer. Methods:A total of 44 cases of normal gastric mucosa,44 cases of atrophic gastritis with intestinal metaplasia,41 cases of low-grade intraepithelial neoplasia,38 cases of high-grade intraepithelial neoplasia and 35 cases of early gastric cancer from Jan. 2015 to Dec. 2016 at the Affiliated Drum Tower Hospital of Nanjing University Medical School were collected. Expressions of Ki-67,p53 and P504s were detected by immunohistochemical staining. Results:Compared with normal gastric mucosal tissue,the positivity rates of expression of Ki-67,p53 and P504s in atrophic gastritis with intestinal metaplasia,low-grade intraepithelial neoplasia,high-grade intraepithelial neoplasia and early gastric cancer were obviously increased (P＜0.05). With the increasing of severity of the lesion,the positivity rate gradually increased. Conclusions:The expressions of Ki-67,p53 and P504s are closely related to the occurrence and development of gastric cancer,and are involved in the early process of gastric cancer. The detections of these molecular markers are helpful for determining the severity and trend of the lesion,and beneficial for improving the detection rates of gastric precancerous lesion and early gastric cancer.