Abstract:Objectives：To explore the case-mix method in diagnosis-related groups （DRGs） and cost standard for the patients with gastric cancer in Nantong city. Methods：The first-page medical records of 5 771 cases of gastric cancer mainly diagnosed from 2006 to 2013 in Nantong cancer hospital were grouped by the decision tree model based on the CHAID algorithms. Validity in terms of homogeneity within groups and heterogeneity between groups was measured by coefficient of variance （CV）and reduction of variance（RIV）. The absolute value method and relative weights were used to calculate the standard. Results：The mean hospitalization expense was 16896 Yuan，and the median length of stay（LOS）was ten days. The main classification node variableswere therapies，first hospitalization，hospital admission approaches，prognosis，complication，and age. 13 diagnosis-related-groups and related health expense standards were established. Conclusion：Case-mix diagnosis-related groups are reasonable，and the health expense standards and related case weight could make references for health insurance department to formulate the payment standard.