Abstract: Tongxin County is the core area in the arid region of central Ningxia. 30 years since the 2nd national soil investigation, soil fertility has undergone profound changes. To understand the soil fertility characteristics of farmland in Tongxin County, 2000 soil samples were collected from Tongxin County from 2008 to 2012. The soil fertility data of these samples were analyzed by using one-way ANOVA and principal component analysis, and compared with the data from the 2nd national soil investigation. The results showed that compared with the data of the 2nd national soil investigation, soil organic matter, total nitrogen and available potassium decreased by 12.2% , 10.5% and 4.8% , respectively, while available phosphorus increased by 121.4% and available nitrogen remained at the same level. The average pH value of farmland soil was 8.77, showing significantly negative correlations with the content of soil total salt, organic matter, total nitrogen, available nitrogen, available phosphorus and available potassium (P＜0.01). Soil total salt was 0.30 g/kg, showing a positive correlation with available phosphorus without significant difference. However, soil total salt was negatively correlated with other soil indexes. The soil organic matter content was 7.08 g/kg, showing significantly positive correlations with total nitrogen, available nitrogen, phosphorus and potassium (P＜0.01). Soil total nitrogen content was 0.57 g/kg, showing significantly positive correlations with available nitrogen, phosphorus and potassium (P＜0.01). The contents of soil available nitrogen, phosphorus and potassium were 36.07, 14.77 and 170.63 mg/kg, respectively, showing significantly positive correlations with each other. It is suggested to use effective methods to increase soil fertility and to balance nutrition supply, such as choosing acid soil conditioner in cultivation to alleviate soil alkalization, emphasizing the application of physiological acid fertilizer.