The invention discloses a preparation method for acetylacetonatodicarbonyl rhodium, which is characterized by comprising the following steps: introducing carbon monoxide into the alcohol solution of rhodium chloride hydrate with the temperature of 60-70 DEG C to react for 60-120 minutes, adding a certain amount of acetylacetonate to continuously react for 60-90 minutes, and separating and recovering the products. The alcohol in the alcohol solution is one or more of methanol, ethanol, 1-propanol and 2-propanol. The concentration of the rhodium chloride hydrate in the alcohol solution is 0.10-1.00 mol/L. The addition volume of acetylacetonate is proper to meet the condition that the molar ratio of the acetylacetone ions contained in acetylacetonate to rhodium is ensured to be 3.0-8.0. The acetylacetonate is one or more of lithium acetylacetonate, sodium acetylacetonate, potassium acetylacetonate, magnesium acetylacetonate and aluminum acetylacetonate.