The invention provides a high-temperature-resistant profile control agent and a preparation method thereof. The high-temperature-resistant profile control agent is prepared from, by mass, 1-4% of melamine monomers, 0.555-4.8% of aldehyde and/or urotropine, 0.5-2% of N,N-methylene bisacrylamide, 0.05-0.2% of plasticizer, 0.05-0.2% of initiator and the balance water. The preparation method of the profile control agent includes the steps that the melamine monomers, the aldehyde and/or urotropine are sequentially added into the water, and a first solution is formed after stirring is completed; N,N-methylene bisacrylamide, the plasticizer and the initiator are sequentially added into the first solution, and the high-temperature-resistance profile control agent is obtained after stirring is completed. The temperature-resistant temperature of the profile control agent reaches 300 DEG C, the sealing capacity of the profile control agent is high, the profile control agent can enter the deep position of a stratum, and the production problems that steam drive oil reservoir steam absorption profiles are not uniform, and inter-well steam channeling occurs are effectively solved.