The utility model relates to a supporting mechanism for a locomotive main transformer dismounting and mounting lifting device. The device comprises a supporting shaft, a supporting frame, a spacer bush, felt, a circlip for a hole, a needle roller bearing set, a roller sleeve, a forced filling oil cup and a baffle, the two support frames are fixed together with a translatable bottom plate of the locomotive main transformer dismounting and mounting lifting device; the supporting shaft is supported by two supporting frames; a groove in the supporting shaft is clamped at one end of the supportingshaft through a baffle; the baffle plate is fixed on the support frame; the inner ring of the needle roller bearing set is positioned with the upper shaft shoulder of the supporting shaft through a spacer bush, the other side of the spacer bush and the other side of the shaft shoulder are fixed in the axial direction through a supporting frame, the outer ring of the needle roller bearing set is sleeved with a roller sleeve and positioned in the axial direction through a left circlip for holes and a right circlip for holes, and felt is installed on the outer sides of the circlips for holes forsealing; a forced-filling oil cup is installed at one end of the supporting shaft. According to the utility model, large load performance can be provided at a low structural height.