A mounting assembly and an inverter assembly using the same are disclosed. The mounting assembly includes a waterproof component and a fixing component. The waterproof component includes a first side facing the inverter, a second side facing the wall surface, an opening and a gasket set. The opening runs through the first side and the second side. The gasket set is disposed around the opening. The gasket set abuts against the wall surface and the inverter. The inverter is electrically connected with a wire running through the opening. The fixing component is disposed on the wall surface and connected to the waterproof component. The fixing component includes a third surface facing the inverter, a fourth surface facing the wall surface, and a first engaging element. The first engaging element engages with a second engaging element of the inverter to mount the inverter on the wall surface.