The invention aims at providing a pyrolysis fuel gas and air rapid mixing device. The pyrolysis fuel gas and air rapid mixing device comprises an outer shell, an inner shell and a lobe mixer, wherein the inner shell is arranged in the outer shell; a hydrocyclone air inlet passage is formed between the inner shell and the outer shell; the lobe mixer comprises a lobe mixing structure inner passage wall, lobe convex structures and lobe concave structures; the lobe convex structures and the lobe concave structures are arranged alternately to form an annular structure; the lobe mixing structure inner passage wall is connected with the annular structure; a lobe mixing structure inner passage pyrolysis fuel gas inlet communicating with a rich oil pyrolysis combustion chamber is formed in the lobe mixing structure inner passage wall; the lobe mixer is arranged in the inner shell, and a lobe mixing air passage is formed between the lobe mixing structure inner passage wall and the inner shell; an inclined radial runner provided with cyclone blades is installed at an outlet of the lobe mixer; and a pyrolysis fuel gas and air mixing gas outlet is arranged at an outlet of the inclined radial runner. The pyrolysis fuel gas and air rapid mixing device can complete rapid mixing of pyrolysis fuel gas and air, and lowers generation of lean burning area NOx.