Abstract: In order to measure the development height of ‘two zones' in No. 3 coal seam roof of Yinxing No. 1 Coal Mine,110301 working face was selected as the test area,and the core,borehole flushing fluid consumption observation,borehole TV and other measurement methods were comprehensively used for measurement,and compared with the theoretical calculation results. The results show that the mutation position of drilling flushing fluid consumption is the highest,and the calculation result of the standard formula is the smallest. The analysis shows that the consumption of flushing fluid can only qualitatively reflect the development degree of cracks,and is easily affected by factors such as the degree of communication between pores and cracks in rock strata. The borehole TV can directly observe the development trend and subtle characteristics of cracks in the vertical direction,with high accuracy and reliability. Finally,the results of borehole TV imaging exploration are taken as the height value of water-conducting fracture zone under the conditions of 3 coal seam goaf,that is,56. 95 m,and the ratio of fracture to mining is 17. 58:1.