Abstract: Due to their large depths and high floor heights， long-span factories require roof skylights to meet indoor ventilation and daylighting requirements. This paper systematically analyzed the ventilation and daylighting methods of long-span factory roof skylights. Ventilation simulation software VENT and daylighting analysis software DALI were used to establish digital models of ventilation and lighting for long-span factories. The characteristics of the wind and daylight environments in factories with and without skylights were compared. Additionally， the performance differences of various skylight forms such as flat skylights， steel roof truss skylights， thin ventilators， and fixed daylighting strips in terms of ventilation and daylighting were analyzed. Based on digital model simulations and field investigations， this study explored the selection of skylight forms under different climate conditions， such as severe cold regions， cold regions， and hot summer and cold winter regions， and proposed design strategies for skylight forms in these regions. By systematically analyzing the differential characteristics of various skylight configurations in terms of ventilation and daylighting performance， and taking into account practical application requirements such as snow accumulation prevention， water seepage resistance and glare control， as well as full-life-cycle comprehensive benefits including durability， service life and operation & maintenance costs， a mechanism for skylight design strategies is established. This mechanism maximizes the utilization of indoor natural daylight and natural ventilation， effectively improves indoor environmental quality， and reduces building operational energy consumption.