A method of producing a heat-resistant crosslinked fluororubber formed body, including: step (1) melt-mixing, with respect to 100 mass parts of base rubber containing 60 to 99 mass % of fluororubber and 1 to 40 mass % of ethylene-based copolymer resin modified with unsaturated carboxylic acid, 0.003 to 0.5 mass parts of organic peroxide, 0.5 to 400 mass parts of inorganic filler, 2 to 15 mass parts of silane coupling agent, and silanol condensation catalyst, in which the step (1) includes, step (a) melt-mixing all or part of the base rubber, the organic peroxide, the inorganic filler and the silane coupling agent at a temperature equal to or higher than a decomposition temperature of the organic peroxide, and step (b) melt-mixing a remainder of the base rubber, and the silanol condensation catalyst, to melt-mix the thus-modified ethylene-based copolymer resin in at least one of the steps (a) and (b).