A heat dissipation system of a portable electronic device, comprising: a first processing element, having a first region and a second region; a second processing element; a heat dissipation module, located between the first processing element and the second processing element; a first heat transferring member, extending from the first processing element to the second processing element through the heat dissipation module, and comprising a heat pipe which is in thermal contact with the first region, the second processing element and the heat dissipation module; and a second heat transferring member, extending from the first processing element to the heat dissipation module, and comprising a heat pipe which is in thermal contact with the second region and the heat dissipation module; wherein the first processing element generates heat from the first region when the first processing element is in a first loading mode, the first processing element generates heat from the first region and the second region concurrently when the first processing element is in a second loading mode, and the heat generated by the first processing element in the first loading mode is less than the heat generated in the second loading mode, the heat generated by the first region is transferred to the heat dissipation module and the second processing element through the first heat transferring member when the first processing element is in the first loading mode and the second processing element is not activated, the heat generated by the first region is transferred to the heat dissipation module and the second processing element through the first heat transferring member, and the heat generated by the second region is transferred to the heat dissipation module through the second heat transferring member when the first processing element is in the second loading mode and the second processing element is not activated, wherein the heat dissipation system is characterized by further comprising: a third heat transferring member, extending from the first processing element to the second processing element through the heat dissipation module, and comprising a heat pipe which is in thermal contact with a third region of the first processing element, the heat dissipation module and the second processing element, wherein the first region and the second region corresponds to a die of the first processing element, and the third region corresponds to a part of the first processing element without the die. a first processing element, having a first region and a second region; a second processing element; a heat dissipation module, located between the first processing element and the second processing element; a first heat transferring member, extending from the first processing element to the second processing element through the heat dissipation module, and comprising a heat pipe which is in thermal contact with the first region, the second processing element and the heat dissipation module; and a second heat transferring member, extending from the first processing element to the heat dissipation module, and comprising a heat pipe which is in thermal contact with the second region and the heat dissipation module; wherein the first processing element generates heat from the first region when the first processing element is in a first loading mode, the first processing element generates heat from the first region and the second region concurrently when the first processing element is in a second loading mode, and the heat generated by the first processing element in the first loading mode is less than the heat generated in the second loading mode, the heat generated by the first region is transferred to the heat dissipation module and the second processing element through the first heat transferring member when the first processing element is in the first loading mode and the second processing element is not activated, the heat generated by the first region is transferred to the heat dissipation module and the second processing element through the first heat transferring member, and the heat generated by the second region is transferred to the heat dissipation module through the second heat transferring member when the first processing element is in the second loading mode and the second processing element is not activated, wherein the heat dissipation system is characterized by further comprising: a third heat transferring member, extending from the first processing element to the second processing element through the heat dissipation module, and comprising a heat pipe which is in thermal contact with a third region of the first processing element, the heat dissipation module and the second processing element, wherein the first region and the second region corresponds to a die of the first processing element, and the third region corresponds to a part of the first processing element without the die.