Abstract: With the modular construction of intelligent substation, the tank type multi-break vacuum circuit breaker (TMVCB) has become a development trend. In order to solve the problems of compact structure and insufficient space of internal equalizing voltage configuration of TMVCB, this paper proposes a new structure of 40.5 kV integrated self-sharing vacuum interrupter (ISVI) based on the ring ceramic capacitor (RCC) and external grading field shield (EGFS). Its structure composition and working principle are analyzed. The 3D electrical model of ISVI is established by using the COMSOL software. The difference between the ISVI and commercial vacuum interrupter is obtained by comparative analysis. The structure size of EGFS, epoxy sealing thickness, RCC parameters, connection mode of EGFS and RCC are optimized. Moreover, the configuration scheme of the ISVI is proposed, and the equalizing effect of tank type series connection is verified. The results show that the ISVI can improve the electric field distribution and the external insulation strength, and the voltage equalizing capacitance of ISVI is about 800~1 200 pF, which can meet the requirements of voltage equalizing between the main shield and the fracture. The paper provides the design basis for the engineering application of the integrated self-sharing vacuum interrupter.