The methods of direct reaction and solvent evaporation are adopted to coat boron powder with PBT. Transmission electron microscope,acidity-instrument and rotary viscometer are used to analyze the properties of the coated boron powder. The results obtained by X-ray photoelectron spectroscopy and transmission electron microscope show that the surface is perfect. The analysis results obtained by acidity-instrument and rotary viscometer show that coating of PBT can improve the value of pH of the solution with boron and effectively reduce the viscosity of propellant. The analysis of combustion residues shows that the burning efficiency is obviously improved after coated by PBT,and the amount of substance proportion between B₂O₃ and B increases from 1：22.7 to 1：8.51.