Aiming at the problem that the visual expression of the precise three-dimensiona l data of mined-out area in Internet is difficult,a 3D visualization method for mined-out area based on coupling of CMS (Cavity Monitoring System,CMS) and VRML (Virtual Reality Modeling Language) in network environment was proposed.CMS is u sed to obtain accurate the 3D spatial data of mined-out area,then the raw data s tored as TXT files are transformed into files with DXF format by CMS-PosProcess software,and the three-dimensional model with DXF format are compiled to files w ith generate WRL format,so the three-dimensional model of mined-out area can be browsed in network directly by IE.The practical results show that the data redun dancy of three-dimensional model generated by coupled CMS-VRML in network enviro nment is small,the effect of visualization is perfect and the interactive perfor mance is good,thereby it provides a new technological means for the safety super vision of mined-out areas in mines.