The compass is composed of a pen head, a rotary shaft, a compass leg, a ruler, a folding leaf, a pen body, a pen tip, a compass tip, and a small ear. The lower end of the pen head is inserted and connected at the upper end of the pen body, the lower end of the pen body is threaded at the upper end of the pen tip, the flush end of the small ear is welded at the middle of the outer side of the compass leg, and the lower end of the compass leg is clamped and connected at the upper end of the compass tip.