According to the theoretical derivation and reorganizing analysis on the engineering test data, comparative analysis was made on the ground settlement under different conditions of natural ground and the site with existing buildings. With the empirical formula of ground settlement in soft soil of Shanghai, the ground settlement curve of existing buildings overload were fitted with visual representation of the size and shape of ground settlement tank as well as the position of the largest settlement. It is showed that the existence of adjacent buildings obviously change the ground settlement curve shape in natural ground, the consideration of the influence by existence of adjacent buildings is related to the correct evaluation and prediction on the safe state of foundation pit and surrounding environment.