The invention relates to a normal pressure microwave plasma generating apparatus, which consists of a rectangular waveguide, a wave-transparent gas seal membrane, a waveguide changeover mechanism, a microwave resonant cavity, a closure end adjustable phase matching unit, a reactor, a flame lighter, an outer layer cooling collar and a rotating air current generating unit. The microwave transmits in the rectangular waveguide, the reactor is disposed on the geometrical center in the resonant cavity which has the air cooling collar installed outside, the flame light is disposed upon a gas reaction tube and the rotating air current generating unit, the combined type insulated high temperature resistant electrode of the flame lighter is disposed along the inner axis of the quartz tube with the end position adjustable up and down freely. The invention achieves the following advantages: adopting the rectangular waveguide and waveguide conversion can make the microwave energy gathered to process higher power; the power capacity can reach 2KW; the close end can adjust the phase matching unit to generate standing wave in the resonant cavity, ensures the microwave energy coupled to the resonant cavity, reduces microwave reflection loss and improves energy utilization efficiency.