Background: Equity in access to healthcare is a major health policy challenge in many low- and middle- income countries. However, millions of people, especially migrants, do not have the adequate access to health care they need. This study aims to identify the socioeconomic status (SES) inequities in inpatient service utilization based on need among migrants by using a nationally representative study in China.Methods: The data used in this study was derived from the 2014 National Internal Migrant Population Dynamic Monitoring Survey collected by the National Health Commission of China. We used logistic regression method and Blinder-Oaxaca decomposition and calculated the concentration index to measure inequities of SES in inpatient service utilization based on need. Sample weights provided in the survey were applied in all the analysis to represent the China population.Results: The total number of the migrants who needed inpatient service told by doctors was 7592, of which, 1667 (21.96%) did not use the inpatient services (unmet inpatient service need). Results showed that inpatient service utilization concentrated among high-SES migrants (Concentration Index: 0.041, p <0.001) and the decomposition results suggested that about 53.76% of the total SES gap in inpatient service utilization could be attributed to the gradient effect. After adjusting for other confounding variables, the odds ratios of inpatient service utilization by internal migrants with high SES according to educational attainment, economic status, and employment status were 1.41 (95% CI 1.08-1.85, p =0.012), 1.25 (95% CI 1.01-1.56, p =0.046), and 1.62 (95% CI 1.12-2.36, p =0.011), respectively.Conclusion: This study observed an inequity in inpatient service utilization where the utilization concentrates among high SES migrants. This suggests that future policies should make the reimbursement more pro-poor among migrants in primary care and use more effective policies targeting the migrants with low educational attainment and unemployed, such as health education activities.