Abstract：Hard roof fall will have great adverse impacts on mining engineering；and it will affect the safety of mining. Generally，the value of distortion or bedding separation of roof may be used as the indicator of roof fall，but it is very difficult to give a definite separation value to forecast roof fall because the separation threshold of roof fall changes with the lithology of roof. A new method using the curve peak segment pattern of separation velocity in roof is presented to forecast the roof fall below separation. A new computer-controlled remote monitoring roof separation and a forecasting roof fall system have been invented. It is shown by the hard roof fall forecast practices in Muchengjian Mine in China that the system is accurate and reliable；and it can forecast roof fall ahead 15–29 hours. The system can provide references to the roof fall predication in various underground engineerings.
