Abstract: The leakage of water from the waterproof curtain will change the distribution of the seepage field and is an important factor in inducing disasters in foundation pit engineering. It is of great scientific significance to develop a method for calculating the water head of the surrounding strata during the dewatering process of foundation pits under leakage of waterproof curtain. Considering the influences of the leakage position of the waterproof curtain on the seepage process of groundwater level, the soil layer of the foundation pit is assumed to be a double-layer foundation. Based on the one-dimensional consolidation theory, the control equations for groundwater seepage at different positions are derived. A method for calculating the water head of formation during precipitation is derived based on the continuous conditions of seepage at the leakage point and the bottom of the waterproof curtain. The accuracy of the theoretical method is verified through the indoor experiments. The results can provide reference for the calculation of water head of formation during the dewatering process of foundation pits under leakage of waterproof curtain.