With the help of the finite element simulation software Msc.Marc,through introducing the deformation theory of rigid plastic compressible materials, the internal rarefaction levels of workpieces were assessed by the relative density,a three-dimensional finite element model for the rolling of big size bars with internal rarefaction was established.The influences of different tensions on the workpieces internal relative density,rolling force and amount of spread were analyzed.The simulation results were verified by the actual continuous rolling experiments of big size bars.The results show that the internal rarefaction in big size bars was reduced effectively by using the negative tension rolling.However,the rolling force,rolling torque and amount of spread increased at the same time.When using negative tension rolling to improve the internal density of big size bars,the factors which determined the size of negative tension such as the mill capacity,the pass-filling degree and so on should be put into consideration.The negative tension stress should be controlled at about 4 MPa in continuous rolling.The simulation results were in general accord with field rolling results.%借助Msc．Marc有限元模拟软件，通过引入刚塑性可压缩材料变形理论，以相对密度表示轧件心部的疏密程度，建立了含心部疏松缺陷的大规格棒材轧制的三维有限元模型，分析了张力类型对轧件心部相对密度、轧制力、宽展量的影响，并结合钢厂大规格棒材实际连轧试验对模拟结果进行了验证.结果表明：负张力轧制能有效改善大规格棒材心部的疏松缺陷，但同时会使得轧制力、轧制力矩以及宽展量增加；采用负张力轧制改善大规格棒材内部组织致密性时，需要综合考虑轧机能力和孔型充满度等因素确定负张力的大小，在连轧过程中压应力的大小宜控制在4 MP a左右；模拟结果与现场轧制结果较一致.
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