A forced-air pre-cooling experimental unit was established. The characteristic curves of Longan ventilation resistance in different experimental conditions were obtained. The relationship between airflow rate and pressure drop was found out. The pressure drop through Longans could be expressed through the Ramsim equation. The pressure drop was proportional to the square of the airflow rate approximately. The effects of shape and area of container venting hole on pressure drop were discussed. At the same airflow rate and venting area, pressure loss is smaller through round vent holes than through rectangular vent holes. When opening areas were bigger than 15.5% of the package surface, then it could meet low pressure loss and had small energy consumption. The results provide foundation and theoretical basis for design of forced-air pre-cooling system.