A cup assembly structure includes a cup which is composed of a body, a panel, a fixing device, and a snap ring. Through a plurality of projection members, a latching piece, and a groove on the body to be fitted and connected with a plurality of concaved holes, an extension end, and a bending end located on the fixing device, and then through a plurality of protrusions on the snap ring to be fixed with a plurality of slideways of the body, the panel which is located at an exterior of the body can be firmly assembled, and the panel of different pattern can be exchanged, so as to increase a visual effect of using the cup.