A hair thinning scissors is provided. The hair thinning scissors includes a first cutting edge and a second cutting edge. The first cutting edge is configured with a plurality of arc shaped cutting teeth. A notch is configured between each two neighboring cutting teeth. Each of the arcuate cutting teeth has a radian by the pivotal axis of the first cutting edge and the second cutting edge as an arc center, and a distance from the pivotal axis to the tooth as an arc radius, so that when the first cutting edge and the second cutting edge are actuated to rotate one toward another, each of the cutting teeth moves along a tangent of the arc form of the cutting tooth, thus achieving a more smoothly shearing operation.