The extremely low-frequency electromagnetic method is a rapid techni que requiring only portable devices. In 1:50,000 hydrogeological survey, this method, in combination with the aerophoto interpretation, has proved to be effective in investigating regional structures at the early stage of hydrogeolo gical survey. In the exploration of fissure water in bedrock, the adoption of detailed extremely low-frequency survey, together with some IP sounding work, can reveal locality and attitude of the fissurecrowded zone and conduct water abundance analysis, thus providing valuable information for drilling.