An efficient method for the synthesis of biologically active 3,5-diaryl-1-cinnamyol-2-pyrazolines is reported. A new series of 1-cinnamoyl-2-pyrazoline derivatives were synthesized by the treatment of appropriate chalcones with cinnamoyl hydrazide using acetic acid in polyethylene glycol-400 as reaction solvent under mild reaction condition. Structures of the newly synthesized compounds were confirmed by the spectral analysis. The advantage of this method is simple work up, shorter reaction time and exclusion of expensive catalyst is reported.