The influence of the distorted plane of the active phased array antenna on the electromagnetic performance is of great significance to the research on and development of the high-performance antennas.On the bent and bowl-shape distortion,the model is established of the relationship between the electromagnetic performance and the position error of the radiated elements.The method is presented of analyzing the far-field pattern of the distorted rectangular active phased array antenna.The analysis results of a planar phased array antenna with different distortions grades prove the validity of the model.Therefore,by the method,the antenna designers may set the reasonable requirement on the structural tolerance in manufacturing antenna.