A ceiling fan blade mounting structure includes a blade holding base and a fastening assembly. The blade holding base includes a plurality of connection members spaced apart from each other. The fastening assembly includes a wedging member, a rotating block, and a fastening member. The wedging member is fastened with one of the plurality of connection members. A first end of the rotating block is rotatably connected to the wedging member. A first end of the fastening member is rotatably connected to a second end of the rotating block. The fastening member is configured to rotate about the rotating block to cause a second end of the fastening member to be fastened with another one of the plurality of connection members.