An airflow orifice adjusting device of a package thermal-shrinking oven includes at least one airflow orifice board mounted to an inside surface of a hot airflow box of the package thermal-shrinking oven and formed with series of airflow orifices, at least one track board mounted to an outside of the hot airflow box and formed with a plurality of track holes, a plurality of adjusting levers, and a plurality of airflow-blocking adjusting plates mounted to the airflow orifice board and each formed with a plurality of adjusting orifices. Each of the airflow orifices of the airflow orifice board discharges a hot airflow. The adjusting levers each have two ends that are respectively formed as a connecting portion and an operating portion. The connecting portion extends through the track holes of the track board to connect to one end of the airflow-blocking adjusting plate, so that a leftward or rightward horizontal moving operation of the operating portion of the adjusting levers causes the airflow-blocking adjusting plate to correspondingly perform a reversely directed horizontal movement in a rightward or leftward direction. The adjusting orifices of the airflow-blocking adjusting plates respectively correspond to the airflow orifices of the airflow orifice board, so that each of the adjusting orifices may completely or partially match with or completely un-match with a corresponding one of the airflow orifices of the airflow orifice board to adjust a discharging flowrate of the hot airflow and discharging of the hot airflow or not.