Abstract: A fan with guiding ribs in a vent comprises a frame body and a supporting part. The supporting part comprises a pivot connecting fan blade and guiding ribs with outside extension, wherein by means of the guiding ribs, the supporting part is disposed on the inner end surface of the frame body and the profile of guiding ribs is to have an inclined plane that gradually shrink from the end surface to fan blades. By the above structure, complicated components in the prior art can be simplified and the resistance generated by the guiding ribs can be reduced as well. Furthermore, the air flow blown from fan blades is guided to further increase pressure output by the fan.