Abstract: One of the basic problems of quantification in geoscience is uncertainty. Based on the concept of probability, the possible value for a variable is pro-posed with the estimation of a single value replaced by probability distribution. The reliability of estimating parameters is further discussed. There are various methods for estimating the reliability of a parameter with probability distribution. Applying the mechanism of feedback, the pro-posed method of feedback combines organically the precision of mathematic computation and the human judgement. Sharp PC-1500 computer is used as the working computer for the study.