The invention discloses a non-jet normal-pressure large-volume microwave plasma generation method, and belongs to the technical field of microwave plasmas. The method is characterized by comprising the following steps: a, starting an igniter, and spraying generated small plasmas or chemical flames into a conical cavity; b, starting a microwave source, and inputting microwaves into a reaction cavity through a microwave feed port; and c, turning off the igniter, increasing the microwave power of the microwave source, and amplifying the small plasmas in the conical cavity to obtain non-jet normal-pressure high-power and large-volume microwave plasmas. According to the invention, to-be-treated gas can be fully and uniformly heated, so that the reaction efficiency is improved; uniform distribution in a set space range is realized, destructive breakdown discharge can be effectively prevented, and heat dissipation balance is easy to control; reasonable temperature, stable structure and long-term operation stability of the whole generator are ensured under the condition of reducing heat dissipation as much as possible; and the whole operation process is simple, reliable and easy to control.