The invention discloses a carriage lifting power switching device of a dump truck. A shell of a power switcher is fixedly connected with a rotary hydraulic pump; an input shaft and an output shaft of the power switcher are supported on the left and right sides of the shell by bearings respectively; one end, in the shell, of the input shaft is sleeved with a driving bevel gear hollowly; the one end, in the shell, of the output shaft is a large head; the input shaft is inserted into a shaft hole at the large head end of the output shaft and is matched with the output shaft by the bearings; a driven bevel gear of the power switcher is supported on a third side of the shell by the bearing and connected with a rotary shaft of the rotary hydraulic pump; the driven bevel gear is always meshed with the driving bevel gear; a synchronous conversion gear and a spline are matched on the input shaft and are positioned between the driving bevel gear and the output shaft; and a shifting fork of a shifting fork mechanism is clamped in an annular groove of the synchronous conversion gear and used for shifting the synchronous conversion gear to move. The carriage lifting power switching device of the dump truck can switch power which is output by an engine to respectively drive wheels or a carriage hydraulic lifting mechanism, so the situation that a carriage lifts during the running of the dump truck is avoided.