The change of heat-induced gelatin hardness, springiness and cohesiveness of PPI (5%) treated under pressure 50~200 MPa for 5 min were investigated and compared with the untreated PPI by various methods including SDS-PAGE, circular dichroism spectra, mass spectrometry and estimation analysis of molecular structure. SDS-PAGE analysis indicated a subunit known as conarachin Ⅱwhit molecular weight 61.0 ku was more sensitive to pressure, and mass spectrometry analysis shown this subunit contained 580 amino acids whose sequence was not changed after pressure treatment and its actual molecular weight was 66.5 ku. Estimation analysis of molecular structure of this unit showed its steric conformation was significantly changed after pressure 100 MPa treatment. Results from CD showed a secondary structure of PPI also greatly changed under high pressure treatment. PPI treated under 100 MPa resulted in the largest value for heat-induced gelatin hardness, increased by 49.6% compared with untreated PPI and reached 172 g, while springiness and cohesiveness remained equal to that of untreated. All the findings above indicated pressure treatment can improve heat-induced gelatin properties of PPI.