A motor and fuel-powered hybrid system of a rocket thruster is disclosed, which mainly provides power through a motor and a fluid fuel injector. In particular, at the beginning stage of the rocket lift-off, the motor drives the compressor to provide power to send the rocket into air. When the speed and height of the rocket gradually increase, the fuel is ignited to give power to keep propelling the rocket, thereby reducing the fluid fuel that needs to be carried on the rocket, increasing the rocket's loading space and enhancing the carrying capacity.