A mounting assembly for a main board in a housing of an electronic device. The main board has an edge contacting the mounting assembly. The mounting assembly comprises a base and a clip. The base is disposed on the housing. The clip is disposed in the base slidably in a first direction and a second opposite direction. When moving in the first direction, the clip fixes the main board, and in the second direction, releases the main board. An acute angle is formed between the first and second directions and the edge.