Abstract: For the structural characteristics of NvShu characters,by combining the basic idea in LLT local threshold algorithm and introducing OTSU algorithm based on maximal between-class variance into local windows,and designing the corresponding modify parameters for the threshold,an image segmentation method for NvShu characters image based on adaptive logical algorithm was presented in this paper,so that the automatic acquisition of local threshold was achieved.Compared with OTSU algorithm,the proposed algorithm not only has strong anti-noise capability,but better overcome the common problem with uneven illumination in NvShu ancient literature.Experimental results demonstrated its feasibility and robustness.