The polyurethane prepolymer was synthesized by using raw materials, including polypropylene glycol, 1,4-butanediol and cationic chain extender Nmethyldiethanolamine. Then, orthosilicate was added to the prepolymer and SiO₂ particles were prepared successfully by hydrolysis of ethyl orthosilicate. Five kinds of cationic aqueous polyurethane emulsions with different contents (mass ratio of orthosilicate/prepolymer) were obtained. The characterizations of emulsion functional group structure, emulsion particle size analysis and heat stability analysis were carried out. The appearance of Si-O bonds in infrared characterization can indicate the successful introduction of SiO₂ particles in the emulsion. Through the particle size analyzer and thermogravimetric analyzer, it can be concluded that with the increase of SiO₂ content, the particle size decreases, the heat resistance is improved, and the surface tension also increases. The preparation of nano-SiO₂ cationic waterborne polyurethane emulsionthe possess good dispersion, stable storage and high thermal stability.