Abstract: Due to the traditional observation method of the similar material test could not effectively obtain the failure zone information of the model, an industrial te st and measuring technology was introduced to the similar material test and observation.The point cloud data of the model surface were obtained with the surface scan ning system.According to the point cloud data features of the model, a collection method of the point cloud boundary was provided.The method was first to collect the cr ack boundary points with the scanning line method, then to connect each boundary with the minium distance method and finally to remove the landmark boundary with t he judgment of the point cloud density and the boundary closed condition.A collection experiment was conducted on the observation data of the model.The results show ed that except some boundary covered with landmarks and with serious cracks, the method could be well to collect the non-continued failure region boundary from the p oint cloud data of the similar material model and the results collected could be applied to the study of the mining subsidence.