A harmonic drive featuring helix-facilitated lubrication includes a circular spline, a flexspline, a wave generator, and an agitating member. The flexspline meshes with the circular spline. The wave generator has a bearing installed within the flexspline, an elliptic wheel positioned in the bearing, and a shaft coupling connecting the elliptic wheel. The agitating member is located in a lubricant-holding space between the wave generator and the flexspline, and has a rotatory part and blade parts formed about a rotatory part. The rotatory part of the agitating member is connected to the shaft coupling of the wave generator, so that when the agitating member is driven by the shaft coupling, the helical blade parts agitate lubricant to perform convection, thereby better lubricating the bearing of the wave generator.