Digital archiving has helped in the development of the exploitation of historical documents, but the number of old documents analysed in national archives and libraries that are specialized in old documents remains very little and dependent on advances in the field of image processing especially thresholding [1]. In this paper we propose a method for segmenting text in ancient documents based on a new hybrid adaptive binarization technique which integrates local and global parameters, in consideration of resolving unsolved problem in thresholding of degraded document images [2] due to the low quality of this type of image, the main idea of our method is to combine the local behaviour and the global behaviour of lighting and contrast variation within the image. The direct application of our approach will improve the quality of processing of old documents, thus character recognition and in-depth analyzes based on contrasts and the types of inks used, will make it possible to better understand the cultural and historical riches existing in old documents.