Abstract: A stirring component includes a body arranged in an internal chamber at a side of a circular spline away from a flex spline of the harmonic transmission system. The body includes a coupling hole through which the body is coupled to and rotated with an input shaft of the harmonic transmission system, and at least one stirring recess arranged on a side of the body adjacent to the circular spline and has a varying depth in an axial direction to stir and push lubricant medium within the internal chamber towards the flex spline during rotation of the body. With the stirring component arranged within the internal chamber, the plate-shaped body can block the lubricant medium from moving further. Furthermore, the stirring component can stir and push the lubricant medium away from the body towards the flex spline.