Abstract: In order to study the effect of protection forests construction on soil nutrient dynamics in Taihu Lake Basin, the experiment was implemented in Yixing City to study the changes of soil organic matter, total nitrogen, total phosphorus, available phosphorus, total potassium and available potassium. The results showed that the protection forests construction could effectively reduce the content of soil nutrients, compared with farmland soil, the reduction rates of organic matter and available potassium content of forested soil were 29.06% and 26.33%, the reduction rates of total nitrogen, total phosphorus and available phosphorus were all over 30%. Hence the research implied that protection forests construction could achieve the effect of source reduction and sink increasing for none-source pollutants, and through source reduction and sink increasing in total, from October 2009 to May 2011, the ecological restoration area of pure nitrogen and pure phosphorus load reduction reached about 46.30-69.54 g/m² and 3.78-7.30 g/m².