A heat dissipating device includes a variable volume unit; a driving unit for driving a volume change of the variable volume unit; and a fluid passage connected to the variable volume unit; wherein the fluid passage includes a heat dissipating section and a heat absorbing section, the variable volume unit and the fluid passage are filled with a liquid coolant; when the driving unit drives the variable volume unit to decrease its volume, the liquid coolant is discharged from the variable volume unit to the fluid passage; when the driving unit drives the variable volume unit to increase its volume, the liquid coolant flows back to the variable volume unit via the fluid passage; the liquid coolant conducts heat to an exterior when it flows through the heat dissipating section, and the liquid coolant absorbs heat from the exterior when it flows through the heat absorbing section.