The theory and method of dislocation model to compute ground surface deformation is introduced. Based on the geological model for ground deformation in Xi＇an city, the relationship between subsidence and 11 underground fissures is discussed and computed with dislocation model. Comparing the results of the calculation with the result obtained by leveling, it is showed that the result computed by dislocation model has the same characteristics as that obtained by leveling in space distribution. It is considered that the subsidence have relation not only with groundwater pumping and surface loading, but also with tectonics of Xi＇an region.