Abstract: Emergency planning zone (EPZ) is one of the important contents in the emergency planning. The study on the EPZ sizing for AP1000, which is the third generation reactor, has significance for its emergency planning and preparedness. At first, the general method for the EPZ sizing and the relevant regulations in our country was introduced. Then, by choosing one coastal site as an example, the offsite consequences were estimated by using the PAVAN and MACCS codes on the basis of the current research results of the AP1000 accidents source terms and the meteorological observation data of this site. Finally, the calculated results were analyzed and assessed with the relevant criteria. This preliminary study result shows that it is appropriate to define the radius of 3 km as inner zone and 7 km as outer zone for AP1000 plume EPZ.