A roller shade actuation device includes a driver arranged in a winding drum, a shaft fixed to a support frame outside one end of the winding drum and inserted into the winding drum, and a transmission mechanism for realizing power transmission between the driver and the shaft. The driver includes a housing relatively fixed to the winding drum, a rotation power member arranged in the housing, and a driving gear coaxial with and fixed to an output shaft of the rotation power member. The transmission mechanism includes a first transmission gear meshed with the driving gear, a synchronous gear coaxial with the first transmission gear, and a fixed gear fixed to the shaft and meshed with the synchronous gear. Axial directions of the output shaft and the shaft are vertical, and the synchronous gear and the fixed gear are bevel gears whose axial directions are perpendicular to each other.