The utility model discloses an adjusting device for a tyre roller chain. The adjusting device comprises a connecting frame used for installing a drive bridge, two groups of support seat, screw rods, and two pull rods, wherein the two ends of the connecting frame are installed on the support seats by virtue of a knuckle bearing respectively, the screw rods are connected with the connecting frame by virtue of thread pairs, the lower ends of the screw rods are contacted with the upper ends of the support seats, the knuckle bearings are in clearance fit to the support seats, each screw rod above the connecting frame is provided with a nut used for location, the pull rods are connected between the connecting frame and the support seats, and each pull rod arranged above the connecting frame is provided with a gland nut used for controlling the connecting frame to be located on the support seats; the nut and the gland nut are unscrewed, the screw rods are rotated to drive the connecting frame to move up and down under the guiding action of the support seats, and the drive bridge on the connecting frame is driven to move up and down to adjust the tightness of the chain. According to the adjusting device, the adjusting operation is convenient, the time and the labor are saved, the assembling requirements of the support seats and the part manufacturing accuracy are lowered, and the production cost is reduced.