Alternative housing systems for laying hens, such as the aviary, promote the expression of dustbathing behavior by providing substrate materials to improve their welfare. However, extensive litter areas in aviaries can lead to reduced air quality and increased incidence of diseases, making them unsuitable for deployment in new large cage aviary unit (LCAU) systems in China. Dust baths have advantages in terms of continuous availability, but their design lacks unified standards. This study explored the effects of different areas, shapes (circular and square), and substrate depths (1 cm, 5 cm, 9 cm) of dust baths on dustbathing behavior in LCAU systems by recording digital video. Each LCAU system was initially populated with 305 Jingfen No. 2 laying hens at 50 days of age. The dust baths were initially placed on the bottommost tier at 66 days of age. The results showed that after approximately 3 weeks of adaptation to dustbathing, the average daily proportion of dustbathing hens within the flock stabilized at approximately 10%. A 50 cm diameter circular dust bath could accommodate their dustbathing requirements. Increasing the number of circular dust baths to 2 did not significantly affect the daily proportion of dustbathing hens. Both the circular dust bath and a 5 cm depth substrate resulted in better expression of the hens’ side rubbing behavior and the lower frequency of tossing behavior.