Using the undisturbed soil samples in soil moisture automatic stations, contrast observation was conducted between manual weighting soil moisture data and automatic soil moisture data at the same time. A serials of manual and automatic measurement data is obtained. The manual weighting soil moisture data are used as standards to calibrate the different depth sensors. Due to the use of undisturbed soil samples, the texture, density, particles, and tightness of the soil samples remain unchanged, the correction equation is more reasonable and accurate. This method can also correct the unreasonable field calibration equation induced by insufficient samples.