In this paper,the co-seismic slip model inversed by the results of InSAR deformation field and precise aftershock location is used to study Maduo M_S7.4 earthquake. The distribution characteristics of co-seismic horizontal deformation field and local stress field are obtained by PSGRN/PSCMP program. Combined with the distribution of deformation stations with co-seismic step around Maduo earthquake,the relationship between the variation of co-seismic stress field and the co-seismic step among deformation stations is discussed. The simulated horizontal deformation field shows that the Maduo earthquake is characterized by the sinistral-strike slip movement. The large horizontal displacements are mainly concentrated in the block of Bayan Har block,followed by the Qaidam block in the north,and the co-seismic horizontal displacement in Qiangtang block and Qilian block is quite small. Kunlun Shankou-Jiangcuo fault is a NE trending strike slip fault. The slip amount in the hanging wall of the fault is significantly greater than that in the footwall,and the maximum horizontal deformation obtained by simulation is about 1380mm. The deformation stations with co-seismic step are mainly distributed in the middle-east section of Qilian Fault zone and west Qinling Mountains area. The Middle-east section of Qilian Fault zone is located in the positive area of co-seismic normal stress variation of Maduo earthquake,while the west Qinling Mountains are located in the positive area of co-seismic shear stress variation of Maduo earthquake,that shows,the deformation stations with co-seismic step have good consistency with the positive area of co-seismic stress field variation.