Magnetic resonance-based wireless power transfer (WPT) system offers a promising solution to provide power for implantable spinal cord stimulator (SCS). To meet with the clinical requirements, the SCS-WPT system should have high transfer efficiency and long transfer distance. As the topology of the resonant network will directly affect the transfer efficiency and output power of the WPT system, a new resonant network, series-parallel and series (S-PS), is selected in this work. The performance of WPT system with S-PS resonant network has been compared with those with the classic resonance networks, it is concluded that S-PS is the suitable resonant network for the WPT system in a wide range of load. Finally, an SCS-WPT prototype with S-PS resonant network is built with detailed parameter design to verify the correctness of theoretical analysis. The system efficiency is up to 68.4% at a coil separation of 50 mm.