Abstract: In order to predict water inflow of an unmining working face, it combined gray theory GM (1,1) model with hydrogeological simulation method in the prediction of water inflow at first time, they had temporal characteristics and spatial characteristics respectively. Then it proposed a calculation method with spatial and temporal characteristics, which was GM (1,1)-hydrogeological simulation method, and it predicted the water inflow for unmining working face, the result was 1 371.4 m³/h. The water inflow value of the working face was 1 369 m³/h by using analytical prediction, the relative error of them was 0.175%. This method could be used to predict the water inflow of unmining working face, which provided a new method for designing the size of temporary water storage in umining working face and determining the drainage capacity.