In the paper, detailed analysis is made on the working principle of ventilations with parallelconnected fans and seriesconnected fans, detailed description of the application conditions and special aspects of ventilations with parallelconnected fans and seriesconnected fans is provided, features of ventilations with parallelconnected fans and seriesconnected fans are presented by means of actual ventilation cases and recommendations are suggested on the application and development of ventilations with parallelconnected fans and seriesconnected fans.