In the process of low-permeability sandstone reservoir exploitation, stress sensitivity takes place with the effective stress rises gradually, which will cause permeability decline. Allowing to the condition of in-situ stress, the study and experiment on the rock core in Jilin oil field Fuxin326 oil layer are presented. The experimental results show that the stress sensitivity of this oil layer is small; the regularity of permeability changes is in accordance with exponential function. The stress sensitivity of high permeability core is larger than that of low permeability core. Moreover, experimental and theoretical analysis shows that low permeability core has a larger permeability loss than high permeability core in loading and unloading process where elastic plastic deformation of rock will happen, which is the major reason that permeability loss can not return completely.