In order to solve the problem of loosening that may occur in the assembly structure of the prior art when the user wants to rotate the inner joint assembly to change the light angle of the lighting device installed in the inner joint assembly during the rotation process, an embodiment of the present disclosure provides an assembly structure with a slot. In the present disclosure, only when a card part is inserted into the slot, can the inner joint assembly and outer joint assembly be allowed to be locked with or unlocked from each other by rotation, otherwise only the inner joint assembly can be rotated relative to the outer joint assembly, but both of them cannot be locked with or unlocked from each other by rotation.