What is claimed is:1. A telecommunication cabinet, comprising:a cabinet body, comprising a cabinet and a telecommunication module disposed in the cabinet;a cabinet door, covering the cabinet body, and comprising an inner side adjacent to the cabinet, an outer side opposite to the inner side, a plurality of coupling holes disposed on the inner side, a snap hole disposed on the outer side, and an installation opening disposed on a bottom side of the cabinet door;a fan module, comprising a supporting frame, a plurality of fans arranged in the supporting frame and at least one elastic clip, the supporting frame comprising a front side attached to the cabinet door and a rear side opposite to the front side, the elastic clip fixed on the front side of the supporting frame and a first bump is disposed on the elastic clip to engage the snap hole, and a plurality of frame holes disposed on the rear side of the supporting frame; anda plurality of coupling parts, inserted in each of the coupling holes and each of the frame holes separately;wherein, when the fan module is placed into the cabinet door from the installation opening, the elastic clip is pressed so that the first bump is positioned in the snap hole, the coupling parts are inserted in the frame holes from the coupling holes on the inner side of the cabinet door, and the fan module is coupled to the bottom side of the cabinet door.2. The telecommunication cabinet according to claim 1, further comprising a pair of brackets connected on a rear side of the cabinet, and the telecommunication cabinet being attached through the pair of brackets.3. The telecommunication cabinet according to claim 1, wherein the cabinet comprises a convex plate disposed on a top of the cabinet, and the convex plate protrudes to top of the cabinet door, and a gap is disposed between the convex plate and the cabinet door.4. The telecommunication cabinet according to claim 1, wherein the supporting frame comprises a first supporting plate located on the front side, a second supporting plate located on the rear side and an air outlet plate connected between the first supporting plate and the second supporting plate, and the air outlet plate comprises a plurality of vent holes.5. The telecommunication cabinet according to claim 4, wherein the first supporting plate comprises a plurality of supporting tabs disposed spacedly, and the supporting tabs elastically abut against the cabinet door.6. The telecommunication cabinet according to claim 4, wherein a number of the elastic clip is two, and two elastic clips are spacedly disposed on the first supporting plate and located between any two supporting tabs.7. The telecommunication cabinet according to claim 4, wherein the at least one elastic clip comprises a riveting section and a bending section, and the riveting section is fixed on the first supporting plate, and the bending section is provided with the first bump.8. The telecommunication cabinet according to claim 7, wherein a pressing portion in a curved shape is disposed on an end of the bending section.9. The telecommunication cabinet according to claim 4, wherein the supporting frame further comprises a mounting plate, and a fold section is disposed on a bottom side of the mounting plate, and the frame holes are disposed on the mounting plate.10. The telecommunication cabinet according to claim 4, wherein the fans comprise an axial fan, and the vent holes of the air outlet plate are disposed correspondingly to an airflow direction of the fans.11. The telecommunication cabinet according to claim 4, wherein a plurality of sustaining plates is disposed on the cabinet door, and the coupling holes are disposed on one of the sustaining plates in the inner side of the cabinet door, and the snap hole is disposed on one of the sustaining plates on the outer side of the cabinet door.12. The telecommunication cabinet according to claim 11, wherein a plurality of second bumps is disposed on the second supporting plate, and a plurality of rails spacedly arranged are disposed on the sustaining plate located in the inner side of the cabinet door, and the fan module is assembled into the cabinet door through the second bumps and the rails.13. The telecommunication cabinet according to claim 1, wherein a coupling tube is disposed in the inner side of the cabinet door with respect to each of the coupling holes, and the coupling parts comprise a spring screw, and the coupling parts are inserted in the coupling tube and movable relative to the cabinet door in a manner of attaching to the inner side.
