A quick assembling structure of leg for table or chair, wherein connecting rods are provided with female formations respectively, and a coupling member having assembly cavities being provided into which the connecting rods can be inserted such that the ends of the connecting rods are pressed against the snap fasteners pivotally mounted in the assembly cavities, and that male blocks provided at the outside of the snap fasteners are engaged with the female formations provided on the connecting rods so as to firmly assemble the connecting rods and the coupling member together. When the connecting rods and the coupling member are to be detached, merely upwardly pull the connecting rods off from the coupling member to release the engagement between them so as to achieve quick assembly and disassembly.