Permeability of concrete was an important part of durability. Osmotic coefficient of gangue concrete was studied by orthogonal test. The test analyzed the influence of coal gangue, fly ash and slag in place of aggregate and cement on osmotic coefficient of concrete. The results showed that compression strength was highest and osmotic coefficient was lowest when gangue was in place of 30% aggregate, fly ash was instead of 20% cement, slag took the place of 20% cement. And gangue in place of some aggregate had biggest influence on the osmotic coefficient in coal gangue concrete. At the same time, its mechanical properties and permeability were controlled in a good condition. Finally, the results could provide useful technical reference to exploit the green building material from gangue.