Abstract: In this paper，we analyzed the surrounding rock deformation features of retained entry and the action mechanism of gob-side support body based on the strata movement characteristics in solid backfill mining. The main factor influencing the deformation and instability of the support body is the lateral force caused by tamping operation．A mechanical model of support body stability influenced by lateral force was established，and the width calculation formula of the support body was deduced．The deformation of the support bodies of different widths was analyzed using numerical simulation method with relevant parameters of Huayuan mine．The result shows that the deformation of the support body can be effectively controlled when its width is more than 2.5 m and it is supported by bolts together with bands and net．The field test proves that the technology is successful and effective；the mechanical model of support body stability as well as the width calculation formula is rational．

Key words: solid backfill mining, gob-side entry retaining, gob-side support body, rational width