The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron radiation light source in China, including a 6 GeV storage ring, a booster ring and a Linac. As a typical low emittance storage ring (LER), the dynamic aperture of HEPS is far smaller than the physical aperture. Hence, a novel on-axis swap-out injection scheme was chosen. The booster ring accelerates the beam from 500 MeV to 6 GeV. To reduce the extraction kick strength, before injection into the storage ring, four slow bumper magnets are applied to assist the kicker to accomplish extraction. The bumper pulse magnetic field waveform is a half-sine wave with 1ms pulse bottom width. Depending on the simulation and test, a classic LC resonance circuit topology with IGBT switching in series with fast recovery diodes is adopted. Besides, an energy recycle circuit is designed, to decrease power loss and reduce the influence on the output pulse current waveform during the capacitor recharge process. A pulsed power supply prototype is developed, and the testing results show that the bumper pulser can fully meet all the requirements of HEPS booster high energy extraction system.