Abstract: To investigate the effects of ultra-high pressure and recombinant pectin methylesterase inhibitor(rPMEI)on the activity and quality of pectin methylesterase(PME)in freshly squeezed orange juice,the effects of ultra-high pressure(400,500 and 600 MPa,5 min,20 ℃)and recombinant pectin methylesterase inhibitor on orange juice microorganisms,PME activity,color and V_C content were studied. The results showed that when the ultra-high pressure treatment condition was 500 MPa/5 min and the rPMEI concentration was 0.06 mg/mL,the total number of colonies,mold and yeast in the orange juice could reach the agricultural industry standard NY/T 434-2016 Green Food-Fruit and Vegetable Drinks,PME was completely passivated;the color change of orange juice was significantly lower than that of the heat treatment group(ΔE*=1.22<2.26);the V_C retention rate was 85.1%,which was significantly higher than the heat treatment group(retention rate=8.33%).