[en] Based on the extension of Young’s interfering experiment, we propose a method for designing double-period graded photonic crystal (GPCs) structure and validate the experiment using multi-fiber interferometry. First, we extend the Young’s double-beam interfering theory to multi-beam interference. According to the simplified multi-beam interference theory and using multi-fiber interfering method, GPCs structures can be designed. Designed patterns can be controlled by positioning of fibers, number of fibers and interference distance. Second, a simple experimental system is built to validate the proposed theoretical model. GPCs structures are observed from the experiment. If we record the structure by using photo-sensitive medium, we will obtain GPCs lens. A good consistence is gotten between the theoretical and experimental results. This method has an important guidance for the design and fabrication of GPCs cylindrical lens and arrays.