Abstract: Due to the non-standard early mining in a limestone mine with transition from open pit to underground mining， there formed a number of goafs in the mine， which seriously affected the safe production of the mine. In order to eliminate the potential danger of goafs， the spatial structure parameters of 12 goafs are obtained and the 3D numerical model of complicated mine goafs are established according to the detection results of 3D laser scanning. Then， the stability of complex goafs are evaluated by adopting the thickness-span ratio method，the simply supported beam model analysis method， the Mathews graphical method and the pillar safety factor method. The results show that the stability of goaf No. 3 and goaf No. 6 is relatively low， and the stability of other goafs is relatively high. The un-stability of goaf No. 3 is due to the large exposed area or span of the roof， and the un-stability of goaf No. 6 is due to the thin roof thickness of goaf.

Key words: Goafs, Stability, Comprehensive evaluation, Safety classification