During general design of solid rocket motor and propellant, experimental study on ignition impact under different state was carried out, which was based on free-loading engine of single root and single-hole charge with PVC plastic propellant and rigid composite modified double base propellant. Its aim is to find the variation rule of impact load along the engine axis in ignition process and propagation speed of the pressure wave in annular channel of the engine. The test results show that the relationship of igniter quantity and igniter pressure is approximately exponential; The pressure of the head of combustion chamber and the annular channel are approximately equal: the pressure wave speed in annular channel of engine does not vary remarkably with the amount of the igniter; Pressure jump generated by the igniter quantity is not occurred within the annular channel in real fire situation.