The invention discloses a preparation method of palladium trifluoroacetate. The preparation method comprises the following steps of a first step, the preparation of a palladium source: putting palladium sponge into hydrochloric acid, wherein the mole ratio of the palladium sponge to the hydrochloric acid is 1 to 2; in a temperature condition of 40 to 70 DEG C, introducing chlorine into an obtained first mixture, making an obtained second mixture react to generate chloropalladic acid, then adding sodium hydroxide of which the concentration is 30 percent into the chloropalladic acid to regulate a PH (Potential of Hydrogen) to 10 to 11, then adding formic acid into an obtained third mixture in a condition of 90 to 100 DEG C until the PH value is 2.0 to 4.0, carrying out heat preservation and a reaction for 1 hour, reducing an obtained product to obtain active palladium, washing the active palladium, and then using the active palladium as the palladium source; a second step, the preparation of a finished product, adding the active palladium made in the first step into trifluoroacetic acid, wherein the mole ratio of the trifluoroacetic acid to the active palladium is (40 to 60) to 1; in a condition of 90 to 110 DEG C, adding nitric acid into an obtained fourth mixture, wherein the mole ratio of the nitric acid to the active palladium is 0.8 to 1.2; carrying out the heat preservation and agitation for 2 to 4 hours, making an obtained fifth mixture react completely to generate the palladium trifluoroacetate, completing a reaction, then cooling and crystallizing a reaction product, filtering the reaction product, so that the rufous palladium trifluoroacetate and filtrate can be obtained, and carrying out reduced pressure distillation on the filtrate to obtain the palladium trifluoroacetate.