Abstract: The genetic algorithm(GA) is used for optimal analysis on the element position and current amplitude of aperiodic arraywith elements arranging in large space, and the optimal parameters are achieved, which make the side lobe level minimum in thescanned area. The effect of element spacing, scanned area and element beam-width on side lobe level and gain of aperiodic arrayantenna is discussed, and the effects of these factors on radiation performance are given. The element spacings when side lobe levelin the scanned area is minimum are acquired by GA optimization, that is used to guide the design.