According to the invention, drying agent, a mildew preventive and the like are mostly adopted for preparation and preservation of a dry coleopteran insect specimen in a dry environment, the requirement for the environment is strict, a temperature and humidity control device needs to be matched, once the specimen is exposed in air for a long time, the specimen is prone to being affected with damp and damaged due to moisture absorption and the like, protectiveness is low, and the specimen protection cost is high. The invention provides a novel preparation method of a dry specimen, which comprises the following steps of: softening, needle inserting, drying, permeating and film forming, so that a film-forming material permeates and treats a substrate of the dry specimen, the appearance characteristics and the form of the specimen are not changed, a non-polar protective layer is formed in a capillary structure of the dry specimen, the moisture resistance of the specimen is improved, and therefore, the service life of the dried specimen is prolonged.