Temporarily occupied space (TOS) is defined as a thermally conditioned space where the majority of people stay for a short period of time (less than 40 min). However, traditional heating in TOS often leads to energy waste (e.g., overheating) or thermal discomfort (e.g., large vertical air temperature difference between head and ankle levels). Therefore, one solution of using ceiling fan in reverse mode is introduced to drive warm air from room high level to occupied zone to enhance heating effect of occupied zone in energy efficient mode. In this study, parameter optimization study of a ceiling fan reversing combined with a diffuse ceiling ventilation (DCV) system is based on the applicability of the system in the TOS heating mode, aiming at balancing short term thermal comfort and energy efficiency. The effects of ceiling fan speed (40–80 rpm), supply air change rates (4–8 times/h), and supply air temperature (26–30 °C) on predicted mean vote (PMV), vertical air temperature difference between head and ankle levels (ΔT), draught rate (DR), and temperature effectiveness (TE) were analyzed by validated CFD model and experimental data, and combined with the characteristics of the TOS to propose a simplified operation strategy.