A control module of a window shade includes a drive axle affixed with a sleeve, an arrester assembled around the sleeve, a cord drum connected with an operating cord, a clutch operable to couple and decouple the cord drum with respect to the drive axle, and a release unit including a stick that is operatively connected with the arrester. The arrester blocks rotation of the drive axle in a locking state, and has an unlocking state allowing rotation of the drive axle. The operating cord is pulled to drive the cord drum in rotation and turn the clutch to a coupling state, such that the rotation of the cord drum is transmitted through the clutch to drive the drive axle in rotation for raising the shading structure. Moreover, the stick is operable to switch the arrester from to the unlocking state for lowering the shading structure by gravity action.