Abstract: Disclosed is a cycloidal pinwheel pair with uniform contact and one-tooth difference, comprising a stator and a rotor. Each gear tooth profile of the rotor has a modified recess provided symmetrically on both sides; the starting point (A) of the modified recess on one side of the gear tooth profile is located between a first point and a second point determined by locations of two limit positions, the end point (B) of the modified recess on the same side of the gear tooth profile is located between a third point and a fourth point determined by locations of two limit positions. By adopting the present disclosure, the internal leakage formed between high and low pressure chambers is effectively avoided, thereby significantly improving the volume efficiency and mechanical efficiency. Meanwhile, the present disclosure is extremely simple in structure and can be molded by one-time grinding with better manufacturability.