The invention provides an array antenna Taylor-Schelkunoff polynomial design method, and relates to a modular array antenna. The method includes the steps that 1, array antenna parameters are selected; 2, the array antenna is divided into at least two modules; 3, a Taylor synthetic method is selected to calculate an array factor directional diagram of the modules; 4, an SPM synthetic method is selected to obtain a directional diagram with null steering, and the null steering angle is made to correspond to the grating lobe angle of the array factor directional diagram; 5, a directional diagram multiplication principle is adopted, the grating lobe of the array factor directional diagram is offset, the low-minor lobe radiation directional diagram is achieved, and the excitation amplitude of all arrays is controlled through the preset null steering angle; 6, if the obtained low-minor lobe radiation directional diagram cannot meet the design requirement, step 2 is executed, and the array antenna is regrouped. According to the array antenna Taylor-Schelkunoff polynomial design method, the excitation amplitude of all the arrays can be controlled through the preset null steering angle, a modular feed network is achieved through an equipower distributor with the phase and impedance being matched, the radiation loss is reduced, and the design and manufacturing cost is lowered.