Abstract: Based upon the theory of cubic spline function with second boundary condition and the method of optimum segmentation in the multiple-element statistical analysis, a software system is built up to process by micro-computer the static sounding data. The system can complete a series of tasks such as data interpreting, calculating and plotting with the Output of all the processing results in the form of charts. The concept of optimum segmentation is expounded with the emphasis on the application results of the system in the engineering practice.