Preparation method of high-temperature-resistant polyester and high-temperature-resistant polyester

The invention discloses a preparation method of high-temperature-resistant polyester. The preparation method comprises the following steps: 1, shearing and emulsifying graphene and ethylene glycol ina mass ratio of not more than 1: 100 to obtain a graphene dispersing agent; 2, uniformly mixing terephthalic acid, ethylene glycol, a graphene dispersing agent, isosorbide, 1, 4-cyclohexanedimethanoland an auxiliary agent, wherein the esterification temperature is 230-260 DEG C, and the pressure is 0.05-0.15 MPa; wherein the mole parts of terephthalic acid, ethylene glycol and isosorbide are 4.5-6.0, 3.0-4.0, 1.0-2.0 and 0.5-1.5 respectively, and ethylene glycol comprises ethylene glycol in a graphene dispersing agent; the content of the graphene is 0.008%-0.01% of the total mass of the ethylene glycol; wherein the auxiliaries are a mixture of an esterification catalyst, a polycondensation catalyst, an antioxidant, a heat stabilizer and a water-carrying agent, and the content of each auxiliary is 0.01%-0.1% of the