Abstract: A mounting structure of a seat for an all terrain vehicle with a vehicle frame and a seat frame, at least one insertion rod is provided at a bottom of the seat frame in a front-and-rear direction, with a rear end of the insertion rod being in snap-fitting engagement with the vehicle frame, the mounting structure comprises a guide carrier fixedly provided on the vehicle frame and having a socket at a rear side of the guide carrier capable of inserting a front end of the insertion rod, with a width of the socket in a left-and-right direction gradually increasing from front to rear, so that the front end of the insertion rod is positioned in an up-and-down direction by snap-fitting engagement into the guide carrier and limited in the left-and-right direction by engagement between inner walls of the guide carrier.