Abstract: The crack as one kind of urban disaster, is bringing more and more tremendous influence on urban construction.How is the ground-fissure extending and its influencing scope, degree and so on is urgent attention and earnestly to solve for city subway construction.Specially the reversed fault as one kind of research form, its research results are relatively few.In order to look into the ground-fissure spreading mechanics reason and extending characteristic in loess, the author incorporated large-scale physical simulative experiment results and numerical simulation results to make verification.The research indicated that the reversed fault has its unique merit in loess expansion.At last, some new meaningful conclusions were drawn.