In order to solve the technical problem of radio fuze anti-sea clutter jamming at ultra-low altitude, the sea clutter model of radio fuze under large incident complementary angle is studied. According to the test data, the sea surface backscattering coefficient of the fuze is studied under the condition of large incident grazing angle. Through physical sea surface modeling and grid division, the random sea surface echo model of the fuze is established, and the theoretical calculation method of sea clutter power is provided. The comparison between the simulation results and the fuze test results shows that the consistency between the model and the measured data is good, which provides a theoretical basis for the analysis of the sea clutter characteristics of the fuze.