The surface description and design methods of annularly piecewise surfaces are proposed. A high-precision transformation method from aspherical surface to annularly piecewise surface is proposed to construct an initial surface, and the optimization strategies, constraints and implementation methods for the annularly piecewise surface are discussed. This proposed surface is employed to design and optimize an ultra-short projection lens. The total length is 155 mm and the maximum distortion is 1.36% after optimization. The research results indicate that this annularly piecewise surface can improve the freedom and flexibility of optical design.