A memory expansion assembly includes a first plate having first electrical slots and a first electrically connecting portion, a second plate pivotally connected to the first plate and having second electrical slots and a second electrically connecting portion, a first engaging assembly, and a second engaging assembly. The first electrical slots are electrically connected to the first electrically connecting portion. The second electrical slots are electrically connected to the second electrically connecting portion. The second plate is adapted to pivot relative to the first plate to have a folded position when the two are close to each other and an unfolded position when the two are away from each other. The first engaging assembly is disposed on a side of the first plate. The second engaging assembly is disposed on a side of the second plate. The first engaging assembly is removably engaged with the second engaging assembly.