Layer system subdivision and adjustment is applied in oilfield development to ease the contradiction in inner-layer and interlayer and implement separated layer water flooding well, which is a major adjustment measure to improve developing effects. YSL is a typical low-permeability oil field, whose petrophysics is poor, and which exist many problems, such as apparent contradictions between layers, and poor development effects through separated zone water injection and so on. In this article, the thickness of barriers, injection profile, permeability contrast and remaining oil distribution are analyzed comprehensively. So a reasonable method is also proposed. Much weakness that factors are not comprehensive in adjustment method and that the problems in the development process are not accurately reflected is overcome, which exists in the past methods. The adjustment means can utilize poor thin layers better, reduce invalid water injection and ease the contradictions between layer, and oilfield development effects are improved eventually. It is a reference and guidance for other blocks or oilfield which exist the same problems.