The solution of the hydrogeological parameters in the condition of the non -stationary recharge flow is concerned with 3 unknown transcendental equations, which can not be obtained by the normal analytic method. This paper used the optimal fitting method to realize alternative of the function relationship of the chart-given non-stationary recharge flow with the simpler functions in the range of the parameters suitable with the engineering, and used the groundwater level decrease ratio relationship to obtain the expressions with only 1 unknown quantity. After simple calculation, the parameters can be obtained.