In order to clear the cause of sand body of the lower Cretaceous in up-salt Kenjiyake oilfield, guiding the oil and gas fields’ development. Therefore, under the condition of dense well pattern, we use the comprehensive data of core, rock slices, analysis and laboratory, ancient biology, well logging and so on to study the granularity, structure, composition of the sand body’s reservoir and the distribution law of sand body. Then the results show that: the reservoirs in Baliemu formation of the middle Cretaceous are mainly fine sandstone and siltstone; Sandstone has some small cross bedding and horizontal bedding; the compositional maturity of sandstone is medium while the texture maturity of sandstone is high. Delta plain that is in the Northwest has the Dual Structure. Vertically ,the upper the sequence,the finer the grain size ; The sand body in the study area is distributed in a single shape, this form has the typical sedimentary characteristics of the meandering river delta; In this areas we have identified delta front, delta plain, frontal delta, shallow lake, including 10 kinds of microfacies: distributary channel, subaqueous distributary channel, shallow lake sand bars, ect．At the same time we have analyzed the distribution patterns of sand bodies and the sedimentary characteristics; During the second member of Baliemu formation period delta front subfacies main distribute in the West of the study area, while in the first member of Baliemu formation period the whole area evolves the former delta - shallow lake subfacies which is the typical retrogradational delta; This study provides important geological basis for the development of Kenjiyake oilfield.