Abstract: From the theoretical study and the indoor experiments, the paper summarized the study status of the water inrush and sand inrush mechanism in coal mi nes and pointed out that the water head pressure of the unconsolidated aquifer in the above overburden strata and the width of the sand inrush channel would be the ke y to set up and represent the mechanics of the water inrush and sand inrush.With the study on the prevention and control measures and the safety evaluation method a pplied to the present production practices, the paper held that the prediction and early warning model should be established based on the comprehensive evaluation on factors influenced to the sand inrush from the mine excavation and mining.According to the some unsolved scientific problems in the sand inrush process from the exca vation and mining, including the quantitative prediction and calculation of the sand inrush, the visualization of the experiment, the excavation and mining risk evaluation and others, the paper provided a view that " the flow behavior of the particle material was applied to deeply understand the mechanics of the sand inrush occurred" .Bas e on the transparent soil experiment technology applied to reveal the mechanism of the sand inrush process from the excavation and mining and the migration law of th e water and sand mixture in the rock cracks and the broken rocks, a sand inrush safety judgment model of the excavation and mining in coal mine was established to pr ovide the technology support to the safety mining under the unconsolidated aquifer.