A guiding device (2) includes a base (21), a cover (23) and a sidewall (22) cooperatively defining an annular space therein and a passage therethrough. An air inlet (221) is defined in the sidewall communicating with the space for an airflow flowing into the space. A plurality of guiding plates (24) are arranged in the space around the passage. An air outlet (29) is defined between two neighboring guiding plates for the airflow flowing out the space into the passage. The airflow is distributed into a plurality of even streams by the guiding plates. An atomizer (4) is connected with the space via the air inlet. The atomizer produces a high-pressured water vapor which is taken by the airflow to cool an aluminum profile produced by an extrusions press (6) and moving through the passage.