Recently in Japan, many buildings introduce packaged air-conditioner (hereinafter, this is called “PAC”) as an air conditioning equipment. Most of the PACs can change the direction of supply air blown from the unit and the “Swinging Mode” can change airflow direction periodically as one of the airflow direction setting of PAC. Before constructing the building, appropriately predicting the indoor environment (e.g. temperature distribution or air velocity distribution and so on) is important for indoor environment design. CFD analysis is one of the simulation technique based on the fluid dynamics and have been used to predict the building environment. However, it will take long time to finish non-steady analysis while analysing swinging airflow with non-steady analysis in CFD, it may cause trouble in design situation. In order to shorten the analysis time and acquire more precise result, the purpose of this research is to establish a CFD model to possibly analyse the swinging airflow in non-steady condition, using dynamic Prescribed Velocity (P.V.) method. In this paper, the experiment to understand the characteristics of the airflow blown from the PAC was carried out. The results of airflow direction measured by an anemometer, airflow volume measured by a cardboard duct, airflow velocity near air supply opening measured by hot-wire anemometer with X-type probe are obtained to establish the CFD model of analysing the swinging airflow with unsteady condition in this study.