The invention belongs to the technical field of oilfield chemistry, and concretely relates to a polyester ether antifoaming agent, and a preparation method and an application thereof. The polyester ether antifoaming agent is an improved type of a polyether antifoaming agent, and the esterification of the polyether antifoaming agent reserves the high temperature resistance, easy dispersion, low surface tension, good stability and other advantages of the polyether antifoaming agent and weakens hydrogen bonds between water molecules and a polyoxyethylene chain, so the lipophilic property is enhanced, the hydrophilic property is reduced, and reduction of the surface tension is facilitated, thereby the activity of the antifoaming agent is high, and the antifoaming ability is enhanced.