After Fukushima accident, people come to realize that multiunit accidents may happen even though the risk is very low. In order to enhance nuclear safety standards and protect the public and environment, it's necessary to consider the impact on emergency planning zone by multiunit accidents. Based on the requirement of general optimized intervention level prescribed by GB 18871, this article calculates the range of emergency planning zone in case of different number of units in accordance with the assumption of multiunit accidents, and then gives some recommendations of the standard in dividing emergency planning zone according to the calculation results. If considering the risk of multiunit accidents, maybe it's necessary to adjust the corresponding national standards, increase the range of inside plume emergency planning zone and properly adjust the range of outside emergency planning zone.