In order to ensure the safe mining of isolated island working face with impact ground pressure，the isolated island working face mining under the condition of a thick and hard rock layer in a mine was taken as the background. Based on the key layer theory of rock layer control and the viewpoint of the spatial structure of overlying strata，the basic characteristics of the spatial structure of overlying strata formed in the isolated island working face were studied through case study，theoretical analysis，and on-site monitoring，as well as the monitoring and identification method and its anti-impact mining design. The formation process and distribution characteristics of the spatial structure of Γ-type overlying strata were identified，and a mechanical model of reasonable width of the isolated island working face under the spatial structure of Γ-type overlying strata and with the abutment pressure as the main assessment index was established and applied for verification. The results show that the isolated island working face under the condition of one side being fully mined and the other side not being fully mined can form a spatial structure of Γ-type overlying strata with the overlying thick key layer，and the implementation scheme proposed in the paper meets the requirements of the field engineering and can ensure normal mining.

isolated island working face  /  thick key layer  /  strata movement  /  impact ground pressure  /  spatial structure of Γ-type overlying strata