The invention provides a groove rail steel rail telescopic adjusting device. The groove rail steel rail telescopic adjusting device comprises a tongue rail, a stock rail, a fastening member and a sleeper, wherein the tongue rail comprises a tongue rail bottom, a tongue rail waist, a tongue rail head and a rim slot; the stock rail comprises a stock rail bottom, a stock rail waist and a stock rail head. The tongue rail and stock rail in the present invention are made of the same groove rail which is identical to groove rails to be welded at both ends and does not need forging processing on the heel end of the tongue rail, so that the required length of the regulator can be easily cut. The tongue rail retains the original rim slot and maximizes the continuation of the rim slot structure of the groove rail. The elastic iron shim plate adopts the eccentric block composite structure, which not only makes it easy to adjust the track gauge and the rail direction, but also the facilitates laying on the curve. The non-working edge of the close contact between the tongue rail and the stock rail adopts a composite slicing surface, which has strong structural stability, high vertical and horizontal smoothness and small expansion resistance, and facilitates making a regulator with different allowable expansion amount.