With the increasing demand for ocean exploration, the construction of an integrated space-air-ground-sea network has become extremely important. However, due to the different properties of air and seawater, as well as the complex and variable marine environment, achieving cross-domain communication between air and sea faces many technical challenges. To deeply explore the current state of innovation and future development trends in air-sea cross-domain communication, the paper constructs a dataset based on patent search results. It investigates the overall patent landscape, global geographical distribution, and key innovative entities. The core patents and technological evolution of three technical branches-direct air-sea cross-domain link-level communication, air-sea cross-domain relay communication, and air-sea cross-domain communication networking are analyzed. The paper also offers development suggestions to Chinese innovative entities in terms of core technology breakthroughs and patent protection and utilization.