The invention provides a wellhead combustible gas safe operation method based on adjustable annular suction discharge aiding. A wellhead safe operation system based on adjustable annular suction discharge aiding is used for achieving a suction effect on wellhead combustible gas. The system comprises a sand discharging pipeline, an adjustable annular suction discharge aiding mechanism, an ignitiondevice, a gas injection unit and a first gas injection manifold, wherein the adjustable annular suction discharge aiding mechanism connects a wellhead with the sand discharging pipeline; inert gas generated by the gas injection unit is provided for the suction discharge aiding mechanism by the first gas injection manifold so as to form a negative pressure suction effect; and the ignition device isarranged at the outlet end of the sand discharging pipeline and ignites the combustible gas discharged from the sand discharging pipeline. The wellhead combustible gas safe operation method based onthe adjustable annular suction discharge aiding has the advantages that a dual-passage suction and gas injection adjustable and controllable nitrogen gas injection suction method can be realized; thesafety risk of natural gas overflowing from the wellhead during open well operation such as trip operation and rubber core replacement performed under the condition of production of a small amount ofnatural gas from the stratum is eliminated; the field operation safety is obviously improved; the gas drilling speed acceleration advantage realization is facilitated; and the method is applicable tothe field of counterflush drilling.