Flue gas online sample gas heating device

The utility model relates to the field of on-line flue gas monitoring, in particular to an on-line sample gas heating device for flue gas. Comprising a heat insulation protection cover and a multi-butterfly-shaped fin heater, and the heat insulation protection cover is located on the outer side of the multi-butterfly-shaped fin heater; the multi-butterfly-shaped fin heater comprises a shell, the left end and the right end of the shell are open, a plurality of fins are arranged in the shell at intervals in the height direction and the length direction of the shell, a plurality of sets of fins are evenly arranged in the length direction of the shell at intervals, each set of fins comprises a plurality of fins evenly arranged in the height direction of the shell at intervals, and the fins are arranged in the shell at intervals. The two ends of the fins are fixedly connected with the front side wall and the rear side wall of the shell respectively, and the fins are in an inverted V shape. A plurality of heating r