The invention belongs to the technical field of paint diluents, and discloses a high-flash-point environment-friendly diluent and a preparation method and application thereof. The coating diluent is prepared from the following raw materials in parts by mass: 40 to 65 parts of tripropylene glycol ether, 20 to 30 parts of cyclohexanediol monomethyl ether, 10 to 20 parts of tetrabutyl orthosilicate, 5 to 25 parts of dipropylene glycol monomethyl ether and 8 to 15 parts of acetic ester. According to the invention, the hydrogen bond accepted solvent is used so that the hydrogen bond is more easily formed between the diluent and resin in the coating, the formation of the hydrogen bond between the resin and resin molecules is avoided, the viscosity of the system can be effectively reduced, the efficient dilution effect of the diluent on the coating is realized, and the prepared diluent has a high flash point which is greater than 68 DEG C, and the diluent belongs to a non-dangerous chemical. The diluent is fresh and non-pungent in smell, healthy, safe, harmless, green, environmentally friendly, good in diluting power, wide in diluting range, capable of diluting conventional coatings in the field, high in film forming speed and compact in paint film.