The invention relates to an emulsion breaking type de-foaming agent for an oil field and a preparation method thereof. The emulsion breaking type de-foaming agent for the oil field is prepared by taking polyether modified silicone oil as a main body and polyethylene polyamine polyether as an auxiliary agent and adding a synergist and a solvent. The polyether modified silicone oil is prepared by taking terminated allyl methyl-terminated polyether and low-hydrogen-containing silicone oil as raw materials and reacting at pre-set temperature under the action of a platinum catalyst. The emulsion breaking type de-foaming agent for the oil field is prepared by uniformly mixing and stirring the following components in percentage by mass: 7 percent to 10 percent of the polyether modified silicone oil, 2 percent to 5 percent of the polyethylene polyamine polyether, 1 percent to 5 percent of the synergist and the balance of the solvent. The emulsion breaking type de-foaming agent for the oil field, provided by the invention, not only has the characteristics of small dosage and high de-foaming efficiency, but also has a certain emulsion breaking capability; the aim of reducing the dosage of an emulsion breaking agent of the oil field and the de-foaming agent can be realized. The emulsion breaking type de-foaming agent can be directly added into a foaming solution and can also be added after being diluted to 5 to 20 times by utilizing a hydrocarbon solvent. The emulsion breaking type de-foaming agent for the oil field is very suitable for treating crude oil of the oil field, especially an offshore oil field.