The invention discloses a method for constructing a tight coupling ultra wide band antenna array based on irregular subarrays. The method comprises the following steps: S1, arranging the irregular subarrays by taking the maximum entropy as a condition according to the antenna scale; S2, enabling input ports of the power divider to be in one-to-one corresponding connection with ports of the T/R assembly through strip lines with equal lengths; S3, acquiring an active directional diagram of each sub-array; and S4, performing amplitude-phase weighting according to the active directional diagram ofeach sub-array to synthesize an overall directional diagram, and optimizing the overall directional diagram to construct and complete the tight coupling ultra-wideband antenna array based on the irregular sub-arrays. The whole feed network adopts a strip line form and is processed in a multilayer microwave circuit board, the profile height of the whole array is hardly increased, the port power distribution can be realized, and the consistency of the amplitude and the phase of each output port is ensured. The method overcomes the defect that the space between the tight coupling array units issmaller than the half wavelength, facilitates engineering application, and is high in applicability.