Shale brittleness and ductility always attract much attention in shale gas exploration and development. The determination of the depth interval of brittle-ductile transition of shale is key to the evaluation of shale gas preservation and hydraulic fracturing. Based on rock mechanics tests,we established a set of methods for determining the brittle-ductile transition zone of shale. The pre-consolidation pressure was determined through uniaxial strain test,and the threshold of over-consolidation ratio( OCR) a...