The invention discloses a method for preparing hydration-resistance CaO clinker and relates to a fireproofing material preparation method. The method includes: adding a certain amount of zircon powder into CaO, molding by compressing into balls and blocks after being mixed uniformly, conducting high-temperature calcination and cold quenching at the temperature of more than 1250 DEG C, and preparing the CaO clinker which is superior in hydrate resistance property. The method for preparing hydration-resistance CaO clinker is simple in process, convenient to operation, capable of effectively preparing the CaO clinker which can resist the hydration. The method firstly proposes that air cooling is conducted on the calcium oxide block body or ball body which is added with the zircon powder after high-temperature calcination at the temperature of 1250-1900 DEG C so that the hydration resistance property of CaO can be improved.