Abstract: According to the current mining technical conditions of an iron mine in Hebei province，research on structural parameters of this mine with subsequent filling is carried out.With combination of Beam theory in material mechanics and Flac numerical simulation，the safe and reasonable span of stope roof is analyzed.The reasonable span is determined to be about 18 m through theoretical calculation.In numerical simulation，three plans with the mining subsequence of “one and every other ones” are adopted to analyze the stress and plastic distribution and displacements under different stope spans.The result shows that with the span of the stope increasing，the stress of the roof and surrounding rock gradually alters from being pressed to being pulled.Especially when the span reaches 20 m，the plastic distribution range of the pillar increases apparently.The greater shear destruction of the pillar raises its possibility of instability.So，the span of 18 m is reasonable for the width of the chamber and pillar，which conforms to the theoretical calculation.Meanwhile，it is suggested that during the process of stoping，stress-strain monitoring of pillar and backfill should be strengthened to ensure safe and efficient mining of ore body.

Key words: Mining with subsequent filling, Structural parameters of stope, Reasonable span of the roof, Numerical simulation