A coupling device of a shading member, includes a frame and two coupling modules. Each coupling module includes a main member fixed to a top or a bottom of the shading member, two positioning members connected to the main member, and two controlling members connected to the positioning members. The positioning members are received in the main member, each of which has a gear to engage a rack of the frame. The positioning members are movable by moving the controlling members to make the gears engage or disengage the racks. As a result, the shading member is able to be assembled or disassembled in an easy way.