A supporting mechanism and a sorting machine, and particularly a supporting mechanism (3) for starting limit between two pivoting connection components. The supporting mechanism is provided with a supporting body (31). The supporting body (31) is provided with a rotating end (311). The rotating end (311) is pivotally connected onto a first component by using a rotating shaft. An annular sliding groove (312) is formed in a section of surface far away from the rotating end (311), of the supporting body (31). The annular sliding groove (312) plays a route guidance role for a locating pin (11) disposed on a second component. A ring of the annular sliding groove (312) is internally provided with a U-shaped clamping groove (313) for clamping and fixing the locating pin (11). A one-way deflecting locating valve plate (32) is disposed at the position of an opening of the U-shaped clamping groove (313) in the annular sliding groove (312). The locating valve plate (32) is disposed on the supporting body (31) by using a
