A transmission assembly and a wheel thereof are presented, and the wheel includes a wheel frame and a tire skin. The wheel frame has a ring-shaped joint surface surrounding the wheel frame, and the joint surface is disposed with at least one slot. The slot has two opposite side walls and at least one stopping wall, and the stopping wall is located between the two side walls. The tire skin is ring-shaped. The tire skin is sleeved on the wheel frame, and attached to the joint surface. The tire skin has at least one protruding rib, and the protruding rib is located in the slot. The stopping wall limits displacement of the protruding rib in a direction of a wheel shaft, and the two side walls limit displacement of the protruding rib in a direction of rotation, thus achieving a good combination effect between the tire skin and the wheel frame.