Abstract: Mined-out area with accumulated water in coal mines is difficult to detect because of its complexity.In TEM detection,there are often additional effects.the paper,from the theory and test,studied the effect of the addi-tional features and detecting characteristics of the curve,and on the basis of these characteristics,the actual engi-neering analysis and interpretation were carried out,drilling verified that mined-out area with water was well lo-calized.