Abstract: The sedimentological characteristics of Chang-6 Oil Reservoir Set in the centre of Ordos Basin are studied,taking the theory and technique of high-resolution sequence stratigraphy,and three grade base-level cycles can be identified,such as short-term,middle-term and long-term.The short-term cycles can be recognized including two kinds of dissymmetry cycles,being deeper upwards and a dissymmetry cycles which becoming shallower upwards.Then seven middle-term cycles and three long-term cycles can be recognized.Furthermore,the paper discusses the differences between base-level cycle and sedimentary cycle comparison methods from such aspects as correlation process,method,cycle interface standard and result.