Abstract: The roof deformation of underground projects is a complex nonlinear process. The single monitoring means is insufficient to determine its roofing stability accurately. Standard deviation of displacement monitoring sample for roofing deformation process is deduced based on mathematical statistics. Three deformation stages for stope roofing, non-deformation, stable deformation and accelerated deformation are characterized according to the fore-mentioned results. Acoustic emission characteristics are analyzed during rock deformation and failure according to the combined analysis results of displacement and acoustic emission. The stability criterion of roof is divided into four kinds of modes. Combined with the engineering example of a mine, the roof failure is accurately predicted during mining process. The result provides a new data processing method for stability analysis of roof of underground projects by improving the accuracy of roof stability criterion.