The utility model discloses a wastewater concentration system for hot air pressure-variable circulating water circulation. According to the system and method, air is heated by a heat exchanger from anair inlet unit to obtain hot air; enabling the hot air serving as carrier gas to enter from an air inlet of a distillation concentration tower, performing convection with preheated wastewater sprayedfrom the upper end of the distillation concentration tower in the distillation concentration tower, and heating and taking away part of moisture in the wastewater by the hot air to respectively obtain wet saturated air and a wastewater concentrated solution; the wet saturated air is firstly compressed by the air thermal compression unit; the condensed water is subjected to phase-change heat exchange through the preheater, steam is condensed to form condensed water and dehumidified air, the dehumidified air enters the air inlet unit through the air expansion unit to be subjected to variable-pressure circulation, the condensed water is naturally discharged, and a concentrated solution in the concentrated solution collection conical hopper is discharged out of the conical hopper from the liquid outlet after being concentrated for multiple times through the wastewater circulation outlet and the pipeline until the target concentration is achieved.