To find a simple and precise method for rigid pile composite foundation is still an urgent problem which is not resolved as yet. A simplified method for calculating its settlement is proposed. The settlement of soil between piles was assumed linear due to the bearing capacity of soil between piles play a little in rigid-pile composite foundation. When the load level of pile is not high, the settlement of pile can be considered linear. If the pile may enter nonlinear even plastic, the load-settlement curve of pile is deemed to satisfy hyperbolic law; thus the nonlinear process of pile can be well considered. According to the mathematic property of hyperbolic equation, the nonlinear load-settlement equation can be deduced by the settlement under the characteristic values of bearing capacity of single pile. For the composite foundation with loading test, the hyperbolic equation of pile can be established by directly using the test curve. Based on the deformation coordination between soil and piles and the static equilibrium equation, the actual foundation settlement can be calculated. On the whole, it is a simplified method for calculating settlement of rigid piles composite foundation. By case studies this method is demonstrated to be not only simple but also be precise and can provide an effective and practical calculation method for engineering practice.