The invention discloses a small chassis structure with an external heat dissipation fin, includes a chassis body, and main board ICs and heat conduction pipes arranged in the chassis body, The top ofthe main board IC is closely provided with a heat conducting press fin, the top of the chassis body is provided with the heat radiating fin located outside the chassis body, the bottom of the heat radiating fin is provided with a heat radiating press fin located inside the chassis body, one end of the heat conducting pipe is inserted into the heat conducting press fin, and the other end is inserted into the heat radiating press fin. Under the connection of the heat conduction pipe, the heat on the main board IC is transferred to the outside of the chassis, which effectively realizes the heat dissipation of the main board IC inside the chassis. At that same time, the heat dissipation fin is externally arranged, the volume of the chassis can be effectively controlled, and the small chassis structure of the invention has the advantage of small volume and good heat dissipation performance.