The invention relates to an accessory for a tent, in particular to a grounding nail of pull wires of a rotatable, telescoping and anchoring type tent. The accessory consists of a rotating rod, a shell nail, an anchor-piece shaft, a movable anchor piece, a drag hook, a shell handle, a rotating handle, a contracting-piece slot and an expanding-piece port, wherein, the top of the rotating rod is provided with the drag hook; the rotating rod is arranged in the shell nail, the upper part of the shell nail is a column and the bottom of which is a self-tapping screw with a cone shape. The side wall of the lower end of the rotating rod is provided with three contracting-piece slots which form an angle of 120 degrees in horizontal direction. Each contracting-piece slot is provided with an anchor piece shaft and a movable anchor piece. The grounding nail of the invention has effective anchoring effect, is able to firmly fix even on the soft ground and is very convenient and labor-saving when being mounted and pulled out of ground.