Abstract: Goaf is one of threats in mines. A 3D laser-scan detection technology was used to detect and obtain the point cloud of its complex-shape effectively,and a goaf triangulation model was built. Goaf triangulation model and section can provide the basis for the design of adjacent stope and the safety analysis of the structures around it. Due to goaf complex shape,how to generate section outline and close model’ s fracture surface was the key research on arbitrary- directional section generation. A new generation algorithm of arbitrary-directional section for complex goaf triangulation model was studied and realized. It has functions including several interactive modes for selecting arbitrary section plane,intersection judgment and extracting intersection line based on simplified intersection criterions,generating sec- tion outline based on adjacent judgment of intersection line,and closing model’s fracture surface which combined with ears-cut,interpolation and triangulation between closed lines. Practical application shows that sections are generated efficiently,section outlines are generated precisely,and model’s fracture surfaces are closed well.