Sources of single-photon in pure quantum states are vital resource for quantum information technologies,and have many important application values in new generation information technology,such as quantum communication and quantum computing.Here,we propose a scheme on the miniaturized and heralded generation of pure single-photon through periodically poled lithium niobate (PPLN) crystal.Under the conditions of group velocity matching and quasi phase matching,a non-degenerate spontaneous parametric down-conversion process is designed to generate frequency uncorrelated photon pairs,thus realizing the preparation of heralded pure state single-photon sources.The parameter conditions of frequency uncorrelation are deduced theoretically,and the yield of photon pairs under different conditions are calculated.It is found that the generation efficiency in the lithium niobate crystal waveguide structure are 4—6 orders of magnitude higher than that in the corresponding bulk crystal under the same parameters.These results will be helpful to improve the purity and the yield of miniaturized single-photon sources,and will play an important role in promoting the further development of integrated quantum optical chips.