Abstract: The height of water flowing fractured zone is an important parameter to ensure the safety of coal mining under water body, in order to scientific guided prediction on the height of water flowing fractured zone development under conditions of mechanized mining, the paper analyzed the factor which affect the height of water flowing fractured zone growth, and summarize the data based on a large number of observations carried out by experts before, and made use of a linear fitting method to give the estimated formula on the height of water flowing fractured zone development under conditions of mechanized mining. Compared with the formula that "Regulations of buildings，water，railway and main well lane leaving coal pillar and press coal mining" given ,the estimated formula is less conservative. Found by the formula given in the Regulations procedure the height of water flowing fractured zone value was less than the measured value, a detailed analysised of this issue, given the expected value resulting in smaller procedures specific reasons. At the same time ,the formula is from mass exploitation of the measured data by the country concluded that it is more suitable from the actual ,to prediction the height of water flowing fractured zone development under conditions of mechanized mining.

Key words: Mechanized mining, Water flowing fractured zone, Prediction formulas, Linear fitting