The invention relates to a microwave source device in the technical field of high-power microwaves, in particular to a compact type narrow-band high-power microwave source for forced stopping of vehicles. The compact type narrow-band high-power microwave source comprises a cathode base, a cathode, an anode outer cylinder, a cut-off neck, an outer slow wave structure, an inner slow wave structure,an output waveguide, a coaxial extraction section, an isolation section, a resonant reflection ring, a rear resonant cavity, a solenoid magnetic field and a supporting rod, and the whole structure isrotationally symmetrical with the central axis. The compact type narrow-band high-power microwave source has the advantages that by using the rear resonant cavity, it is ensured that miniaturization and high efficiency are achieved, a peak value with an optimal effect can be generated on the beam-wave effect, and long pulses are easily achieved. By using the resonant reflection ring, the peak value with the optimal effect can be generated on the beam-wave effect; by using the inner and outer double corrugated rectangular slow wave structures, the radial dimension of the outer slow wave structure is reduced; the inner slow wave structure is of a rectangular structure, and the inner slow wave structure and the outer slow wave structure form the double-rectangular structure, so that the axiallength is shortened.