Currently，polymer materials are processed by high temperature plasticizing and low temperature molding． These processing needs to spend a lot of energy and causes the degradation of polymers and additives， reducing product performances and recovery． Therefore，this article introduces highfrequency electric field into hotpressing process of polymers，making the materials plasticize in synergism of normal stress field and highfrequency electric field at low temperature． The dependence of pressure and temperature on thermalresponse of polymer materials to the high frequency electric field，as well as the mechanical properties of pure polymer plates which are prepared at critical plasticizing temperature point， is studied in depth; a model of temperaturerising is also reasonably established． The results show that the stronger polarity of polymer materials， the higher dielectric loss and absorbed heat will be; the absorbed heat of polar materials and amorphous polymer are positively related to the processing pressure，while the absorbed heat of non-polar crystalline materials have the best pressure point in which materials absorb the maximal heat． Homo-polymer have the best temperature points for heat absorption，while the absorbed heat of copolymer exponentially increase with the processing temperature rising． The tensile properties of specimens with highfrequency electric field improved significantly when compared to the specimens without highfrequency electric field，proving the existence of plasticizing behavior at low temperature under the synergism of normal stress field and  highfrequency electric field