With the rapid development of urban greening, the urban greening soil need to be modified and a lot of modified materials are springing up. Furthermore, the measuring method of pH value as the essential measure index for soil and modified materials should be unified. Therefore, the pH value of the soils and modified materials selected from different areas in China were determined with the saturation extraction method, and the compare with the traditional methods were also carried. The results showed that the pH values determined by the saturation extraction method and the traditional method had a significant correlation. And the CO2 in distilled water and the extraction time had hardly an effect on the pH value. Thus, the saturation extraction method will be optimum for urban soil and modified materials.