Abstract: In order to study the influence of the existence of hard clay layer on pressure behavior in the fully mechanized top-coal caving face in thin bedrock,and take Sima coal mine No.1101working face as the research target,the theoretical analysis,numerical simulations and field measurement method were adopted to research overburden strata structure and pressure behavior of working face in thin bedrock.Results show that the existence of clay layer to a certain extent bears the load of overlying sand layer,and formed the more stable structure combined with thin bedrock.With clay layer thickness increasing,support pressure peak forward transfer and decreased strength of pressure behavior.Guaranteeing the early safe mining in No.1101 mining face and good economic efficiency was obtained.