A thrust converting mechanism for a gauge-changing wheelset of a train, comprising: a mounting base , provided with a horizontal through hole along a horizontal direction; and a jacking shaft , movably disposed in the horizontal through hole in a penetrating manner, an open hole being provided in one of the jacking shaft and the mounting base at an engagement position between the jacking shaft and the mounting base , the open hole having an axis perpendicular to an axis of the horizontal through hole, a positioning piece being mounted in the open hole and connected with the open hole by an elastic preloaded piece; the other one of the jacking shaft and the mounting base being provided with a positioning recess matched with a positioning end of the positioning piece; wherein when the positioning end of the positioning piece is located in the positioning recess, the jacking shaft is in a locked state; when the jacking shaft is subjected to a thrust so that the positioning end of the positioning piece disengages from the positioning recess, the jacking shaft is in a movable state; characterised in that the mounting base comprises a base body (101-1) and an extending base (101-3) extending to a side along the base body (101-1), and the base body (101-1) and the extending base (101-3) are connected by a frustum-shaped transition connecting base (101-2) having a large end connected with the base body (101-1) and a small end connected with the extending base (101-3), and a periphery of the base body (101-1) is provided with connecting holes allowing connecting pieces to pass through in order to mount the base body (101-1) on the outer end of an axle-box body, and the horizontal through hole penetrates through the extending base (101-3), the transition connecting base (101-2) and the base body (101-1). a mounting base , provided with a horizontal through hole along a horizontal direction; and a jacking shaft , movably disposed in the horizontal through hole in a penetrating manner, an open hole being provided in one of the jacking shaft and the mounting base at an engagement position between the jacking shaft and the mounting base , the open hole having an axis perpendicular to an axis of the horizontal through hole, a positioning piece being mounted in the open hole and connected with the open hole by an elastic preloaded piece; the other one of the jacking shaft and the mounting base being provided with a positioning recess matched with a positioning end of the positioning piece; wherein when the positioning end of the positioning piece is located in the positioning recess, the jacking shaft is in a locked state; when the jacking shaft is subjected to a thrust so that the positioning end of the positioning piece disengages from the positioning recess, the jacking shaft is in a movable state; characterised in that the mounting base comprises a base body (101-1) and an extending base (101-3) extending to a side along the base body (101-1), and the base body (101-1) and the extending base (101-3) are connected by a frustum-shaped transition connecting base (101-2) having a large end connected with the base body (101-1) and a small end connected with the extending base (101-3), and a periphery of the base body (101-1) is provided with connecting holes allowing connecting pieces to pass through in order to mount the base body (101-1) on the outer end of an axle-box body, and the horizontal through hole penetrates through the extending base (101-3), the transition connecting base (101-2) and the base body (101-1). <EOS>