Abstract: Openpit iron mines are affected by geological disasters such as slope landslides,caving,deformation instability,debris flow,collapse etc,or by ore production demand and price changes,the stripping ratio should be adjusted.The development of mining,mineral processing and smelting technology leads to great changes in ore grade.It is inevitable that some large openpit iron mines are not suitable for the preliminary design of mines in the middle and late stages of production,therefore,it is necessary to carry out the boundary optimization engineering to correct it so as to obtain the necessary security and good economic benefits.Taking a largescale openpit iron mine in China as an example,the necessary of boundary optimization of the mine is analyzed from the aspects of resources,safety,economy and organization technology,and the principles of safety,reasonable recovery of resources and economy should be followed in boundary optimization are summarized.The results before and after boundary optimization is discussed.At the same time,the problems encountered in the process of boundary optimizing the implementation of the mine and the measures should be solved are analyzed and discussed so as to provide reliable reference for similar mines.

Key words: Large openpit mine,Boundary optimization,Slope safety,Ironbearing rock