The window/door opening behavior of occupants is a very important factor in determining the airflows and ventilation conditions in buildings, on which indoor pollutant concentration and transport are highly dependent. A two-room residence model was simulated in this study to analyze the airflow characteristics and pollutant transport under different window/door opening behaviors. Airflows were unidirectional and the residence could not be treated as a well-mixed zone when there were no temperature differences. If there were temperature differences, two-way airflow occurred at the exterior window of the room when it was open and the interior door was closed, resulting in a much larger ventilation rate than the situation without temperature differences. Strong two-way airflow occurred at the interior door in the case of the exterior window closed and interior door open, as the air in the two connected rooms was well mixed after the interior door was opened for tens of minutes. The ventilation rate of the room with double-sided ventilation was much higher than that of the room with single-sided ventilation, even though the total opening areas were the same. Opening the exterior window and closing the interior door could effectively remove pollutants from a polluted room and prevent their transport to a clean room. Field experiments were performed and the main conclusions of the simulation were verified.