Abstract: The effects of ultrasonic time on the MgO nanoparticles′ dispersion properties in the propylene glycol were studied by the absorbance and sedimentation tests.The surface modification of MgO nanoparticles with coupling agent was also researched.Results showed that，MgO nanoparticles had the best dispersion performance in propylene glycol while the dosage of dispersant polyethylene glycol was 1%（mass fraction） and the ultrasonic time was 10 min.The optimal conditions of surface modification were as following: the dosage of aluminate coupling agent was 8%（mass fraction），modifying time was 2 h，and rotary speed of ball miller was 900 r/min.The dispersibility and stability of modified MgO nanoparticles became better in propylene glycol than that of unmodified one.

Key words: MgO nanoparticles, coupling agent, Propylene glycol, stability