In order to study the effects of the air change rate ACH, the fresh air ratio r and the air conditioning energy saving ratio φ on the airflow characteristics distribution and particle diffusion in an empty electronic clean room, a simplified three-dimensional clean room model has thus been constructed for this purpose, followed by an analysis of the airflow characteristics, ventilation conditions and particle concentration changes at typical indoor locations by using the numerical simulation method. The results show that an increase of ACH, r or φ can all enhance the airflow velocity in the vicinity of the indoor personnel and the operating platform area. With the increase of ACH and r, the ventilation effect can be promoted at the pedestrian breathing height, while the change of φ has a great impact on the ventilation of indoor personnel and the operating platform area. The particle concentration decreases with the increase of ACH, while the particle diffusion in different areas of the room is affected by r differently, and the concentration of particulate matter in the vicinity of different indoor personnel varies greatly, with the increase of φ generally reducing the concentration of particulate matter in the vicinity of indoor personnel.