A novel compound constructed from polyoxometalate (H3PW12O40, PW12) and poly(amidoamine) (PA) was prepared at room temperature in an aqueous solution by an impregnation method. A series of novel 1,3,5-triaryl-2-pyrazoline derivatives was synthesized by the reaction between chalcone and phenylhydrazine in the presence of the title compound, PW12/PA, in high yields. The structures of the compounds obtained were determined by IR and 1H NMR spectra.