The impact of water on catalyst activity remains inconclusive due to its dependence on the specific reaction environment. To maximize the exploitation of water's promoting effect, we employed ammonia selective catalytic reduction (NH 3 -SCR) as a probe reaction and proposed a phosphorus modification strategy for Cu-ZSM-5 catalysts. The objective of this approach was to construct water-adaptive microstructures through directional arrangement. To investigate the effect of phosphorus on the transformation of framework copper sites in humid environments, we conducted comprehensive characterizations and density functional theory calculation. Results reveal that water molecules cleave the oxygen bridges between phosphorus oxide and copper, leading to the formation of active isolated [Cu(OH)] + groups and phosphate. The phosphate species weaken the interaction between exchanged Cu 2+ groups and the zeolite framework, leading to the generation of highly migratory hydrated Cu 2+ species. This work will potentially guide the rational design of water-adaptive catalysts for gas pollution abatement in a humid environment.