A method for managing motion responses of a moored aquaculture cage under irregular wave action is disclosed, which pertains to the field of motion attitude calculation technology for marine engineering structures. The method comprises: according to given parameters of a JONSWAP spectrum, obtaining an irregular wave height time series and deriving the wavelets via FFT; simulating a reproducible irregular wave load by wavelet superposition within a numerical wave tank; and, based on the VOF model and overlapping grids, utilizing locally refined grids in critical regions of the flow field and applying a fluid-structure interaction method to simulate the attitude response of the floating aquaculture cage structure within a catenary mooring system under irregular wave loading in the numerical wave tank. The method eliminates the need for prolonged computation, and allows the application of identical irregular wave loads to different targets.