As a new type of power source for vehicle, the internal combustion linear generator integrated power system (ICLG) has its novelty and special operation mode. A free-piston single-cylinder four-stroke SI-engine was used for ICLG. The experimental bench was used to measure flux characteristic, and the selected electronic injector has been tested to ensure its dynamic flux characteristic and ensure if it was suitable for ICLG. By experiments, the dynamic flux characteristic curve of the selected injector was obtained and the formula of computing injected fuel under certain pulse was also verified. The results laid foundation for the further research on ICLG.