Abstract: In order to automatic soil moisture observation data more accurate, better services for the practical application and the application in scientific research, based on the theoretical analysis of automatic soil moisture observation and manual measured value of the error and the correction methods, through the formula , the average value of soil bulk density and soil bulk density on behalf of correction for each calculation, analysis and evaluation of the feasibility of calculating soil gravimetric moisture content in the soil bulk density correction. The results show that: the soil bulk density correction formula is reliable, the use of automatic measurements of soil moisture content and soil bulk density correction formula to calculate the soil moisture is feasible, theory can cancel every eight observation, also provides a guide for practical application, automatic soil moisture observation data for automatic sensor biennial assessment.