The quaternary ammonium salt functionalized methoxypolyethylene glycols-supported phosphotungstic acid catalyst was prepared and characterized using X-ray diffraction, fourier transform infrared spectroscopy and thermogravimetric analysis. The immobilized phosphotungstic acid catalyst exhibited excellent catalytic activity and selectivity, which was shown to be an efficient heterogeneous catalyst for catalyzing the esterification of carboxylic acids with alcohols under mild conditions. The catalyst could be separated by simple separation and can be used six times without significant losing of catalytic activity and selectivity.