Compared to traditional theatres, experimental theatres have a lower floor height and the lights are closer to the audience. The large vertical temperature gradient caused by the underfloor air distribution (UFAD) system extremely impairs thermal comfort. Thus, an improved method by introducing the ceiling displacement ventilation (CDV) system was evaluated. CFD models of the experimental theatre were established and verified by field tests. The influence of designing and operation parameters of the CDV systems on thermal comfort was investigated. Effects on energy consumption and air quality were also analyzed to improve application feasibility. The results indicated that the increment of air temperature at the audience head (AHA temperature) was reduced by 51.0% with the help of the CDV system. Thermal comfort was improved as the installation height was extended higher. Furthermore, under constant total air supply rate, the AHA temperature of the last row was decreased with the increase in the air supply ratio of the UFAD to CDV systems (RUtoC), and the total power consumption was declined by 3.1% through adjusting RUtoC compared to the traditional UFAD system. Additionally, the air quality could be significantly improved. The results are helpful to the design and operation of HVAC systems in experimental theatres.