A kind of preparation method of 3,5,5-trimethyl-3-cyclohexene-1-ketone: with 3,5,5-trimethyl-2-cyclohexene-1-ketone (α-IP) As a raw material, the former nitrogen phosphatrane base is used as a catalyst, and reactive distillation technology is used to carry out isomerization reaction to prepare 3,5,5-trimethyl-3-cyclohexene-1-ketone (β-IP), product β The purity of ‑IP can reach 99.5wt%‑99.8wt%, and the reaction selectivity can reach 99.2%‑99.9%. The process has the advantages of less catalyst consumption, high selectivity, no alkali precipitation, less high boiling matter, etc., and is an efficient synthesis process.