Abstract: The pre-consolidation pressure(pc) of soil is an important index that describes the force history of soil.Solving the pre-consolidation pressure of soil by Casagrande drawing method is usually affected by human factors and complicated to calculate.Through studying Casagrande empirical drawing method, we put forward an improved calculation method that is realized by computer programming.In this method, the collected data points are defined as the beginning and end points of the Bessel curves segmentally, and the definition equations of the Bessel curves are given.We then calculate the curvature points of each section of curves, and finally we derived the maximum curvature points by comparing each curvature point.The new method is compiled into corresponding calculation programs by VBA and EXCEL programming to facilitate the application.It shows that this method can reduce the influence of human factors and possesses better adaptability to test data, thus it is worthy of promotion in determining pre-consolidation pressure in geotechenique engineering.