A heat dissipating assembly, adapted to be disposed at an M.2 expansion card and configured onto a main board with the M.2 expansion card, is provided. The heat dissipating assembly includes a first heat dissipating member and a first double-end screwing member. The first heat dissipating member is adapted to be disposed on the main board, located between the main board and the M.2 expansion card, and has at least one first through hole. The first double-end screwing member includes a first thread and a first nut having a first screw hole. The first thread passes through one of the at least one first through hole of the first heat dissipating member and is detachably fixed to the main board. The first nut presses against the first heat dissipating member.