Loaded MnO2/γ-Al2O3 catalysts were prepared through the ultrasonic impregnation method with γ-Al2O3 as a carrier. Combined with the analysis of X-ray diffraction, X-ray photoelectron spectroscopy and CO2 temperature-programmed desorption, their catalytic activities in the alcoholysis of urea and 1,2-propylene glycol to propylene carbonate were investigated. The results showed that MnO2, which was prepared through the calcination of Mn(NO3)2 as the raw material, exhibited the highest activity due to the existence of the strongest alkaline centers on its surface. Comparison with the traditional impregnation method, Mn on the surface of MnO2/γ-Al2O3, which was prepared through the ultrasonic impregnation method with the 30% loading amount of Mn (mass percentage content), was tetravalent and highly dispersive, and the alkalinity of the basic center was the best. When it catalyzed the alcoholysis of urea, the yield of propylene carbonate was up to 65.0%.