In order to improve the accuracy of groundwater transport simulation, groundwater resources assessment, and land subsidence prediction, the variation of hydraulic parameters of an aquitard during water release was analyzed through laboratory testing. Based on the analytical solution of the water release quantity of an aquitard under the condition that the drawdown of the adjacent aquifer is constant and the flow in the aquitard is stable at the initial time, a type curve method for calculation of parameters is proposed, and experimental research was carried out using the self-developed test equipment. The experimental results show that the hydraulic conductivity and specific storativity decrease gradually with the water release from the aquitard, but the consolidation coefficient changes little. The hydraulic conductivity and specific storativity of the soil layer in the experiment were decreased by 52% and 59%, respectively. The assumption that hydraulic parameters are constant will lead to a significant error in the calculation of the water release quantity of the aquitard. The calculated water release quantity of the aquitard is larger than the actual value when the specific storativity in the initial stage of consolidation is used, but the opposite conclusion is obtained when the specific storativity in the final stage of consolidation is used.