The invention provides a dexamethasone acetate oral tablet, which comprises a drug-containing adhesive layer and a water-insoluble protective layer; wherein a plasticizer in the water-insoluble protective layer adopts triethyl citrate. The invention also provides the preparation method of the dexamethasone acetate oral tablet, which comprises the following steps: 1) dexamethasone acetate is dissolved after added with absolute ethyl alcohol and then added and mixed with dextrin and part of carbomer for granulation, and drug-loading particles are obtained after drying and rounding; 2) the rest of carbomer is drily pressed for granulation, so as to obtain carbomer particles; 3) the drug-loading particles obtained from the step (1) and the carbomer particles obtained in the step (2) are mixedwith magnesium stearate for being pressed into tablets; and 4) spray coating liquid containing polyacrylic resin II, the triethyl citrate, titanium dioxide and a coloring matter is sprayed on the surfaces of the tablets. The dexamethasone acetate oral tablet prepared by the invention is good in uniformity among different batches and low in fragility, thereby improving the stability of the tablet quality.