The invention discloses a preparation method for ambrox, which belongs to the technical field of daily chemicals. The preparation method employs a cheap and easily available molecular sieve as a dehydrating agent and prepares high-quality ambrox through dehydration and cyclization of the molecular sieve and diol-ambroxide in an organic solvent, wherein the molecular sieve used as the dehydrating agent can be cyclically reused. The method has the advantages of small environmental pollution, low cost, convenient post-treatment, suitability for industrial production, etc.