In order to assess the stability of a tailing dam, all hidden geological structures must be identified under a tailing dam. A geophysical survey using associated electrical profile method and high-density electrical method was conducted at the tailing dam site of Xiadianzi iron ore processing plant in Kuandian County. The survey with associated electrical profile method shows that there is a fracture zone abnormality with a strike of 25 degree north-east and a dip toward south-east. The fracture zone presents the characteristics of low dip and compress-sheared. The results can be directly applied to assess the stability of the tailing dam.