The invention belongs to the field of research of engines and discloses a stroke increasing type rotor engine of an electric car. The engine comprises an outer-end stator, an inner-end rotor, a cooling fluid system and a lubricating system; the outer-end stator is provided with high pressure air chambers, high pressure fuel gas chambers, a cooling fluid chamber, a lubricating fluid inlet and a lubricating fluid outlet; the inner-end rotor is provided with at least two symmetrical blind cavities; combustion chambers and exhaust chambers are arranged inside the blind cavities; an exhaust mechanism is arranged between each combustion chamber and the corresponding exhaust chamber, so that the combustion chamber forms a closed combustion space; the pressure ratio of the high pressure air chambers to the high pressure fuel gas chambers is equal to the distribution ratio of fuel gas to air; the center of the inner-end rotor is connected with a center shaft through a spline, power is output, and the center shaft is connected with the outer-end stator 1 through a bearing. By improvement of the rotor engine structure, usable fuel is methane, carbon monoxide or other renewable energy, dependence of an existing power source on traditional energy is relieved, and the power performance and economical efficiency of the electric car are improved.