The invention provides a die-casting mold releasing agent and a preparation method thereof. The die-casting mold releasing agent is prepared from, by weight, 15%-18% of modified organic silicone oil, 3.2%-4% of oxidized polyethlene wax emulsion, 10%-12% of oleate emulsion, 1%-2% of Turkey red oil, 3%-5% of emulsifier and the balance water. The preparation method comprises the steps that (1), the modified organic silicone oil, the oxidized polyethlene wax emulsion, the oleate emulsion, the Turkey red oil, the emulsifier and the water are weighed according to the proportion for use; and (2), the modified organic silicone oil and the emulsifier are mixed firstly and then put into a high-speed shearing disperser, the silicone oil is emulsified through a reverse emulsifying method at normal temperature to obtain a silicone oil emulsion, then the oxidized polyethlene wax emulsion, the oleate emulsion and the Turkey red oil are added into the silicone oil emulsion, all the materials are mixed to be uniform to obtain a mixed emulsion, and then the mixed emulsion is subjected to homogenization treatment through a high pressure homogenizer, and therefore the die-casting mold releasing agent can be obtained. The die-casting mold releasing agent is good in high temperature resistance, the spray quantity of the mold releasing agent is small, the die-casting circulating period is shortened, and the production efficiency is improved.