A cycloidal pin wheel harmonic transmission device includes camshaft, flexible bearing, flexible wheel, roller pins and rigid wheel. The flexible bearing is mounted on the camshaft with elliptical shape. The flexible wheel has inner ring cooperated with outer ring of the flexible bearing, and outer teeth surface contacted with each roller pin. The roller pins are evenly disposed inside semicircular groove of the rigid wheel. The flexible wheel is fixedly connected with inner ring and the rigid wheel is fixedly connected with outer ring of the main bearing. Both teeth height and root have cycloidal teeth profiles reduces the risk of breakage failure, possible to obtain larger engagement without deep engaging distance. Teeth width is large, used for the engagement, the surface specific pressure is small. It is possible to withstand large torque to reduce the amount of deformation of the flexible wheel, and to greatly improve the longevity.