From the continuation of pore distribution, the uncertainty in quantity for the wettness of the capillary moisture bound disruption and the classification of soil water moving stages is discussed. According to the measured data of the moisture thermodynamic functions in the soil-plant-atmosphere continuum, we identified the limitation of the principle of entropy increasing and the suitability of the principle of partial molar gibbs free energy decreasing when judging the direction of soil water movement. Moreover, a further interpretation is made on three basic points of the second law of water flow and the misunderstanding when using the law.