Abstract: The soft soil water-tight oil storage is one that stores oil products bv taking advantage of the static pressure of unoerground water surround-ing the structure, with water sinking into the storage and then being pumped out. Therefore, the sinking rate must be calculated in the design of such oil storage in order to determine discharge capacity.Based on Darcy's Law and giving consideration to the impact of the structural lining upon sinking flow, the paper comes up with equations to calculate the sinking flow-rate of the soft soil water-tight oil stora-ge, typical examples of calculation being presented.