The invention relates to an oil displacement method for improving tertiary oil recovery rate of a high-temperature and high-salt oil reservoir. The method mainly solves the problems of poor temperature and salt resistance and low oil displacement efficiency of a polymer-containing oil displacement agent in the prior art. According to the oil displacement method for improving the tertiary oil recovery rate of the high-temperature and high-salt oil reservoir, the underground dehydrated crude oil is in contact with an oil displacement composition to fully displace the crude oil in the rock core under the injected water conditions that the oil displacement temperature is 60 to 70 DEG C, the total mineralization degree is more than or equal to 20,000mg/L and the total amount of calcium ions and magnesium ions is more than 500mg/L, wherein the oil displacement composition comprises the following components in percentage by weight: (1) 0.01 to 5.0 percent of sulfonated temperature and salt resistant copolymer, (2) 0.01 to 5.0 percent of fatty alcohol-polyoxyethylene ether carboxylate surfactant, and (3) 90.0 to 99.98 percent of injected water. According to the technical scheme, the method well solves the problems, and can be used in tertiary oil recovery of oil fields.