A heat dissipation device for dissipating heat form a heat source includes a control unit, a sensor, a first heat dissipation module, a second heat dissipation module, and a driving mechanism. The sensor electrical connects with the control unit and detects a temperature of the heat source, and reports the temperature to the control unit. The second heat dissipation module is retractably connected to the first heat dissipation module. The driving mechanism is electrically connected to the control unit and the second heat dissipation module. When the temperature exceeds a first temperature, the control unit informs the driving mechanism to extend away from the second heat dissipation module with respect to the first heat dissipation module.