The invention discloses a drill stem (tubular pile) halfway rotating tool. The drill stem (tubular pile) halfway rotating tool comprises an upper joint, a halfway rotating spline shaft, a halfway rotating key groove shaft, a small end cap and a lower joint, wherein the lower portion of the outer surface of the halfway rotating spline shaft is uniformly provided with several splines axially, two ends of the splines are chamfered, the halfway rotating spline shaft is sleeved in the halfway rotating key groove shaft, the inner surface of the halfway rotating key groove shaft is provided with axially through elongate key grooves and semi-closed short key grooves near the middle in a staggered manner, the width and the pitch of the elongate key grooves and the short key grooves are matched with the key width and the distance of the splines, the upper portion of the halfway rotating key groove shaft is connected with the small end cap, the small end cap and the halfway rotating spline shaft form slidable and rotary seal fit, the lower portion of the halfway rotating key groove shaft is connected with the lower joint, and the upper portion of the halfway rotating spline shaft is connected with the upper joint. By the drill stem halfway rotating tool, the drill stem can rotate or slide, and wear and resistance reduction effect is similarly remarkable. Meanwhile, operation is facilitated, length of the upright can be reduced and drilling cost can be lowered.