n order to study the caving rule of overlying surrounding rock by sublevel caving method without botto mpillar, 3DEC discrete element numerical simulation software was used to study the No. Ⅴorebody of Chengchao Iron Mine. In this study, the progressive falling process of overburden, the critical caving span of overburden surrounding rock, the height of caving zone and its movement range are analyzed in different mining paths. The height of caving zone is evaluated by empirical formula, and the vertical stress variation between overburden surrounding rock and the first-mining section surrounding rock is also studied. The results show that: When the span of the gob is about 27m and the average height of the gob is 2m, the first caving phenomenon of the overlying surrounding rock is observed. After that, with the stoping of seven approaches in turn, the height of the caving zone is stable at about 20.7m. The numerical simulation results are consistent with the theoretical value of the empirical formula. In addition, the vertical stress of the overlying surrounding rock and the first mining section surrounding rock gradually increases with the mining of seven approaches one by one, and the maximum stress is 38.59MPa. This study verifies the applicability of the empirical formula of limit caving span and caving zone height on No. Ⅴorebody of Chengchao Iron Mine, and provides reference for related engineering practice.