Abstract: The first middle section of Zhangzhuang Iron Mine is about to end.The horizontal thickness of ore body of -390 m new middle section increases,and the height of the mining stage changes from 60 m to 85 m.In order to ensure the safe stope mining step by step in the highstage stope and ensure the production capacity of the mine,the orebody thickness is divided into two kinds of stope layout according to the recommended safe stope length of 140 m,and the isolated ore pillar is divided into two forms: discontinuous and uninterrupted.The stress variation trend of isolated ore pillar in two forms and six groups of size schemes is analyzed by using the finite element method of 3Dσsimulation calculation.The results show that when the orebody thickness is 100~140 m,10~12 m wide intermittent isolation pillar can be adopted;When the thickness of ore body is more than 140 m,continuous isolated pillar with width of 18~20 m is adopted.The above results provide a theoretical basis for safe and efficient stope mining.