An inter-propellant seal (IPS) for high thrust turbopump is designed. With given operating conditions and requirements, the inter-propellant seal is designed to satisfy the leakage characteristics which is less than 0.1% of normal flow rate of pumps. A numerical analysis is developed to predict the leakage flow rate. The results show that the maximum leakage of LOX and kerosene are less than 0.1% of normal flow rate of pumps, respectively. Based on the numerical analysis results, the detail of IPS is performed. Finally a prototype of IPS is manufactured to perform sets of performance tests in the near future.