The invention relates to a vernier device for a holding head load of a movable car lifting jack. The vernier device for the holding head load of the movable car lifting jack comprises a driving mechanism and a driven mechanism, the driving mechanism comprises a driving end holding head added plate, a hand wheel, a big gear, a pinion, an adjusting lead screw, an adjusting nut, a driving end holdinghead, a hand wheel shaft and a driving end sliding rail pair, the hand wheel, the pinion and the hand wheel shaft are in key connection, the pinion is in meshing transmission with the big gear, the adjusting nut is in press fitting interference fit with the big gear, the adjusting nut is in transmission with the adjusting lead screw, the adjusting lead screw is fixedly connected with bolts through the driving end holding head, and the driving end holding head is fixedly connected with a sliding block of the driving end sliding rail pair through the bolts; and the driven mechanism comprises adriven end holding head added plate, a driven end holding head, a spring shaft, a spring and a driven sliding rail pair, the driven end holding head is fixedly connected with the spring shaft throughthe bolts, and the driven end holding head is fixedly connected with a sliding block of the driven sliding rail pair through the bolts. The vernier device for the holding head load of the movable carlifting jack is simple and convenient to operate, relieves the labor working strength, and improves the working efficiency.