Based on data of different soil types,the conversion of soil texture by mathematical methods including cubic spline interpolation,square spline interpolation and linear interpolation was studied.The result showed that cubic spline interpolation is superlative and the minimum relative error is 0.6%,the maximum error 3.5%,average 2.48%.The development of the texture conversion by mathematical method is valuable for calculating soil erodibility K based on data of soil properties and is meaningful for calibrating soil erodibility nomograph.