The invention discloses an eight-unit L-shaped subarray application method and an application device based on modularization. The method comprises the steps: eight eight-unit L-shaped subarrays are selected, and the eight eight-unit L-shaped subarrays can realize 8*8 square modules with different internal splicing structures and same outlines; a plurality of 8*8 square modules are formed; 20 kinds of 8*8 square modules made of the random-distributed L-shaped subarrays are selected from a plurality of 8*8 square modules and serve as a module selectable set; in the module selectable set, a plurality of 8*8 square modules are randomly selected, and the selected modules are spliced into a target antenna array; according to an array antenna far-field pattern superposition principle, a target antenna array pattern assessment array organizing method is calculated, if the performance of the target antenna array pattern is suitable for index requirements, the splicing process is finished, otherwise, another splicing method is reselected until the respliced target antenna array satisfies the index requirements. The invention also discloses the device corresponding to the method.