Abstract: The isolated island face determination is an important basis for coal mine safety supervision. In order to accurately determine the island attribute of the working face, a method for determining the island attribute of working face under a typical conditions is proposed based on the coal column size effect analysis. Combined with a mine engineering conditions, the size effect of the coal column in the west and north wing of the 305 working face was analyzed by theoretical analysis and engineering analogy. The results showed that: the coal column bodies of the west wing and north wing of the 305 working face did not cause large-scale serious damage of the coal rock mass due to excessive stress concentration. The leading support pressure range of the 305 working face was less than 120 m, which was significantly smaller than the width of the coal column in the north wing. The width of the extreme balance zone of the lateral support pressure of the 305 working face is 52.3 m. The coal column body in the west wing of the 305 working face is wider than the sum of the two extreme balance zones. The west and north wings of the 305 working face are not gob areas. The 305 working face is not an island working face.