Abstarct: The aim of this study provide a suitable method to explore the groundwater located in the joints, the gaps, and hard rock cavities. Nowadays, geophysical methods, particularly geoelectrical methods, is one of the most important methods in hydrogeological exploration, which one of its subsidiaries, is the electrical resistivity method. This method has been used extensively in the study of the Lateral inhomogeneities and vertical electrical properties of the earth and groundwater exploration. According to mathematical models calculated by Telford and Keller, Pole- Dipole array can offer better replies in the Lateral inhomogeneity and vertical Dyke, Compare with other array. So, in this study the electrical resistivity method with two symmetry Pole- Dipole array is used to explore groundwater in Cretaceous limestone located in northern Shahrood. Resistivity measurements have been done with two arrays along a line profile which perpendicular to that along the two parallel faults. Parallel to the one of the fault plane, two water wells have been drilled that are called water wells Twin here. Acquired data from these measurments are processed with two-dimensional inverse method of modeling with RES2DINV software. Reason for choice the Location measurements near the wells above mentioned is the possibility to compare results obtained using the modeling method, with the subterraneous Geological situation region (depth of water level in the Cretaceous limestone), is possible. Finally comparison shows that the Sections obtained from the modeling, shows two faults in the alluvium below that the wells mentioned have been drilled in the crushed limestone near the southern fault plane.