The invention discloses a fluorosilicone rubber / chloroprene rubber sealing gasket for a high-temperature oil pump and a preparation method thereof. The sealing gasket is prepared from fluorosilicone rubber, chloroprene rubber, polyvinylidene chloride, diisobutyl phthalate, wollastonite powder, zinc oxide, magnesium oxide, nano aluminum oxide, dibutyltin dilaurate, nano titanium dioxide, dicumyl peroxide, modified nano-diamond, acetylene black, ammonium polyphosphate, magnesium hydroxide and other raw materials. The sealing gasket has excellent high-temperature resistance, can work at the temperature of 250-300 DEG C for a long time, has quite small mechanical strength and quite small volume changes, and has reliable sealing performance; and the sealing gasket has good corrosion resistance, is resistant to various media, has good air impermeability, is suitable for oil, water, gas, chemical media or other mixed media and the like, and realize effective sealing functions on oil, water, air, coal gas and various chemical media.