The utility model discloses a transistor and a heat dissipating device thereof. The heat dissipating device of the transistor includes a semiconductor base, a transistor working component and a semiconductor thermo-electric effect device. The thermo-electric effect device includes a semiconductor compound layer, a metal film, a metal layer, a heat conducting layer, a thermocouple heat conducting device, a power supply arm and a heat dissipating layer. The transistor working component is arranged on a surface of the semiconductor base. The semiconductor compound layer is arranged on a surface of the semiconductor base that is opposite to the surface with the transistor working component. The metal film is arranged on the semiconductor compound layer. The metal layer is arranged on the metal film. The heat conducting layer is arranged on the metal layer. The thermocouple heat-conducting device is connected with the power supply arm and both of the thermocouple heat conducting device and the power supply arm are arranged on the heat conducting layer. The heat dissipating layer is arranged on the surface of the thermocouple heat conducting device that is far from the surface of the heat dissipating layer. The heat dissipating device of the transistor provided by the utility model can export heat of the transistor quickly and dissipate the heat out, so that the reliability of a power amplifying tube and surrounding components can be improved distinctively.