The authors reported previously that a possible beneficial effect for lenticular pneumatic structures can be obtained by not controlling internal air-pressure but instead setting an appropriate initial internal air-pressure which prevents the membrane structure from becoming unstable under strong winds. The principal aim of this study was to develop a method of setting this internal air-pressure. Firstly, dynamic data was collected through wind tunnel tests using both a rigid and a flexible model for the purpose of understanding the wind pressure coefficient under strong winds and the dynamic behavior of fluctuating internal air-pressure. Next, a time-history wind response analysis was performed to evaluate the fluctuating internal air-pressure under strong winds, and then compared with the results of flexible model by the wind tunnel test. Finally, a methodology for setting the internal air-pressure was proposed based on the data obtained from the static and the dynamic numerical analysis.