Determination of water absorption capability in low permeability reservoir has the important reference value for flooding-development, speculating the water-flood effect and configuring corresponding construction facilities.This paper uses data of exploratory well to get the average capillary pressure curve of reservoir, and then determines the capillary radius and pore volume of reservoir rock contributing to the seepage, and calculates the daily water absorption capability of ideal capillary bundle modelaccording toPoiseuille-equation.On that basis, the model and fluid correction factorsf1andf2have been introduced to calculate water absorption capability eventually.Analysis on comparison between the actual data and the calculated results are basically the same, which indicates that the method has certain reference value in oil-field development.