The invention discloses room-temperature curing adhesive based on silazane and modified silazane polymer and a preparation method thereof. The silazane and the modified silazane polymer refer to one or more of polysilazane, polyborosilazane, polycarbosilazane, polysiloxazane and ceramic precursor polymer containing silicon-nitrogen bonds. The silazane-based ceramic precursor polymer can achieve room-temperature curing under the action of isocyanate, and room-temperature curing high-temperature-resistant organic silicone adhesive is prepared by compounding corresponding packing. The adhesive has high temperature resistance and still has quite high shearing strength at 1,000 DEG C. The adhesive has good thermostability, mechanical performance and adhesive performance, and the temperature resistance of the adhesive is superior to that of phenolic resin; compared with inorganic adhesive, the adhesive has excellent toughness.