Abstract: Based on the data from the Second Soil Census in 1982 and the 2008 National Formula Fertilization Project by Soil Testing, a research was made into the spatial and temporal change of soil pH in Changxing, Nanxi, City of Yibin, using the SPSS17.0 and ArcGIS9.0 software. The results showed that the soil of Changxing was generally acidic, which was more acidic in the north while less acidic in the south. The farmland soil pH ranged from 4.2 to 9.4. Over a period of nearly 30 years, the soil pH reduced from 6.8 to 5.9 with a sharpest decrease detected in the submerged paddy soil which was developed in purple sand shale, from the Shaxi Temple Group.