Through multi-beam coherent surface plasmon polaritons (SPPs) excited by p-polarized light beams, and optimizing exposal parameter of interference lithography, high resolution and contrast periodicity nanometer structure is obtained by using the features of short wavelength and near-field enhanced effect. The principle for nanometer photon-crystal fabrication by the method of multi-beam coherent SPPs intervening is expatiatedon. The relation between the magnetic-field distribution and the light beam number is conducted. The interference field tends complicated with the rise of beam numbers, and the simulation results are given. The intensity distributions of tri-beam SPPs interference and exposure with six-beam SPPs interference are simulated, and the results of interferential exposure about modulation technology are analyzed. The method is suitable for fabricating nanometer photonic crystal and deep sub-micrometer periodic patterns in large field size used in opto-eletronical components, and it can reduce cost effectively.