Transglutaminase (TGase) was used to modify peanut protein isolate (PPI) and the effect of different incubation time (30min, 90min and 240min) on the functional properties of PPI was studied. The results showed that TGase cross-linking induced the change of PPI subunits and the formation of high-molecular-weight polymers. when the incubation time of TGase cross-linking was increased, the decrease in solubility of PPI was observed. It was found that limited TGase cross-linking (37 ℃, 90 min) could obviously improve the emulsion stability of PPI but overtreatment could result in the decrease of emulsion activity and stability. The increase of Td and the decrease of ΔH showed by DSC analysis further proved that TGase cross-linking could increase the thermal stability of PPI.