The Space Plasma Environment Research Facility (SPERF) currently under construction at the Harbin Institute of Technology in China is a user facility dedicated to studying space plasma physics on the ground. A coil system of the SPERF consists of seven types of coils, which are used to generate the magnetic fields and plasma required by the physical experiments. A dipole coil of the coil system works with four magnetosheath coils (flux cores) to build the magnetic fields resembling that of the Earth and solar wind. A capacitor-based pulsed power supply (PPS) system with a modular design is developed to excite the dipole coil to generate a magnetosphere-like magnetic field required by the magnetopause magnetic reconnection experiment. The PPS of the dipole coil has a longer pulse duration and more energy than that of other coils in the coil system, it delivers a pulsed current with a peak of more than 18 kA, and the duration of the current is not less than 95% of the peak over 10 ms to the dipole coil when the charging voltage is not less than 20 kV. The detailed design of the PPS is discussed in this paper, and the discharge test of the PPS is carried out to verify the design of the PPS.