In order to ascertain the details of karst voids in the proposed site and combine the engineering geological and hydrological conditions in the area, a method combining three-dimensional direct current parallel high-density electrical method and transient electromagnetic method is adopted to explain and infer the karst voids by using the respective advantages of the two methods. The results are in accordance with the drilling data. It is proved that this combined geophysical method has good application effect in Karst exploration.