Improving the aeration efficiency of traditional microporous aerator by changing the surface wettability is of great significance to improve the efficiency of sewage treatment. In this paper, Janus aluminum foil with asymmetric wettability on both sides is prepared by laser bionic manufacturing technology. Janus aluminum foil is applied to the self-made aerator to produce uniform ultra-fine bubbles for high-performance aeration, so as to speed up the decomposition efficiency of ammonia nitrogen by nitrifying bacteria in aerobic biofilm and improve the efficiency of wastewater treatment. The results show that the decomposition rate of ammonia nitrogen using Janus aluminum foil aerator is nearly three times that of double-sided superhydrophobic aluminum foil. This simple and low-cost method of laser manufacturing Janus aluminum foil shows great potential in improving oxygen mass transfer and energy efficiency in sewage treatment process.