There were 7 apparent resistivity stations operating within 450km from the epicenter of 2008 Wenchuan M_S8.0 earthquake. These stations recorded different types of changes before the main shock. In this paper,a fault virtual dislocation model is adopted by loading the coseismic sliding displacement of the earthquake in the opposite direction,in order to calculate the stress-strain distribution that can be accumulated to produce these coseismic dislocations before the Wenchuan earthquake. The calculated results showed that at a depth of 100m,the main accumulation areas of normal stress and shear stress before the earthquake were located within about 100km on both sides of Longmenshan Fault zone,and the maximum stress variation was up to 0.5MPa. The volume strain accumulation areas were approximately as same as the stress accumulation areas,and the maximum strain value was up to 10^-5. The degree of stress-strain accumulation was rather low outside these areas. Both stations in Chengdu and Jiangyou were located in the main stress-strain compression accumulation area before the earthquake. The apparent resistivity data recorded at Chengdu and Jiangyou stations declined before the main shock,stepped quasi-coseismicly,and rose after the earthquake,which was accompanied by the stress-strain accumulation before the earthquake and release after the earthquake. The abnormal changes of these two stations were closely related to the Wenchuan earthquake. However,for other 5 stations,i.e. Ganzi,Wudu,Mianning,Xiaomiao and Tianshui,which were located in areas with weak stress-strain accumulation,in consequence,the apparent resistivity changes might be correlated rather weakly with the Wenchuan earthquake.