A method for preparation of the fuel-air mixture provides for feeding into the flow of the fuel-air mixture a flow of a gas medium in the form of separate jets. Each jet of the gas medium is directed tangentially to the imaginary circumference (5) oriented coaxially to the flow of the fuel-air mixture and having the diameter (d) equal, approximately, to 0.2-0.8 of the diameter (D) of the cross-section of the flow of the fuel-air mixture, and the flow from the gas jets is brought to the value of the coefficient ( alpha ) of excess oxidizer in the fuel-air mixture of, approximately, 0.9-1.0. A device for preparation of the fuel-air mixture comprises a casing (8) with a main opening (9) and an annular distribution chamber (10) which is connected to the casing through channels (11), is mounted coaxially to the main opening (9) and is connected to a gas medium source through a feeding channel (12). The axis (14) of each channel (11) is oriented tangentially to the imaginary circumference (5) oriented coaxially to the main opening (9) and having the diameter (d) equal, approximately, to 0.2-0.8 of the diameter (D) of the main opening (9). A consumption regulator (17) is mounted on the section (16) of a feeding channel (12), located in the casing (8).