Abstract: Based on the support failure problem caused by floor heave in soft floor rail roadway of semi coal rock for a coal mine under the complicated hydrologic geological conditions, it used a combination method of field measurement, numerical simulation and theoretical analysis to study the deformation and failure mechanism of soft floor rail roadway of semi coal rock under the complicated hydrologic geological conditions. Then it proposed the support measures for soft floor rail roadway of semi coal rock under the complicated hydrologic geological conditions, determined the combined support technology of reversed arch with bolt-mesh-shotcreting, bolt-grouting and concrete, and determined the parameters and process of combined support.