The invention provides a high-power microwave hole interior fracturing device for an engineering rock mass. The high-power microwave hole interior fracturing device comprises a high-power microwave generator, a high-power microwave coaxial heater, a high-power low-loss microwave coaxial transmission line and a microwave power self-adaption adjusting and controlling system; the high-power microwavegenerator comprises a continuous wave magnetron, a permanent magnet, a wave guide excitation cavity, a coaxial annular device, a coaxial matched load, a coaxial coupling converter, a wave guide coaxial converter and an output wave guide; the high-power microwave coaxial heater comprises a transmission line interior conductor, a transmission line exterior conductor, a microwave input joint, a microwave short circuit seal cover and a conductor supporting cylinder; the high-power low-loss microwave coaxial transmission line comprises an input end coaxial line, middle segment coaxial lines and anoutput end coaxial line, wherein the input end coaxial line is connected with the output end coaxial line through a plurality of middle segment coaxial lines which are connected in series; the microwave power self-adaption adjusting and controlling system comprises an impedance matching adjuster, a microwave power controller and a temperature sensor, and the real-time matching of impedance is carried out on the microwave power through the impedance matching adjuster.