The utility model provides a blow formula blast pipe in commercial car and fixed knot constructs thereof, the blast pipe is including the gas outlet blast pipe and the tail pipe that communicate each other, the lower extreme of gas outlet blast pipe is put through with the EGP gas outlet mutually, fixed knot constructs including support and pull rod, tail pipe's lower extreme is fixed on the support, the one end of pull rod is fixed on the support, and the upper end at tail pipe is fixed to the other end, the gas outlet blast pipe pass through metal collapsible tube with tail pipe and put through mutually, metal collapsible tube and tail pipe pass through large flange fixed connection, one side of large flange is used for realizing being connected of metal collapsible tube and tail pipe, and the opposite side is fixed with the support. The utility model discloses simple structure, each part size is little, weight is little, high position installed is convenient to but active absorption manufacture error and installation error, effectual, the long service life of damping.