An external auxiliary heat dissipation device includes an external connection head module, a fluid driving module, a heat dissipation module, and a plurality of first pipes. The external connection head module includes a first carrier body and at least two first fluid connection heads disposed on the first carrier body. The first pipes connect to the first fluid connection head, the fluid driving module, and the heat dissipation module to form a first fluid pathway. The electronic system includes an internal connection head module and a plurality of second pipes. The second pipes connect to the internal connection head module to form a second fluid pathway. The internal connection head module is detachably connected to the external connection head module, so that the first and the second fluid pathways are in fluid communication with each other to form a loop fluid pathway.