This study proposes the hybrid ventilation system and its design methods for high-rise buildings. The proposed hybrid ventilation system uses natural driving power for ventilation based on air flow in the whole building and indoor and outdoor pressure distributions. Furthermore, it solves the troubles of the conventional natural or mechanical ventilation systems. This paper presents theories and a process for duct design for natural ventilation which forms the basis of a hybrid ventilation system in high-rise buildings. Also, the validity of the proposed design method will be analyzed by simulations.