Abstract: Discrete global grid systems(DGGS) are digital reference models with multi-resolution for earth and its structure supports the fusion processing of multi-source geospatial information. The icosahedral DGGS have aroused wide attention for their excellent geometric properties and the research difficulty is the code operation scheme for the spherical hexagonal grid system currently. It is proved that DGGS based on the regular polyhedrons are topologically equivalent to the relative regular polyhedral grid systems and their schemes for code operation are topologically equivalent as well. According to this, combining the characteristics of the aperture 4 hexagonal grid system on the surface of the icosahedron, this paper defines vertex tile and face tile based on hexagon lattice quad tree and proposes the code operation scheme for the icosahedral aperture 4 hexagonal grid system. This scheme realizes the cross-face operation of cells using code operation with high efficiency and overcomes the drawback of existing schemes brought by the use of floating numbers for cross-face operation with low efficiency. In addition, the search efficiency for cross-face adjacent cells is about 19.6 times that of hexagonal quad balanced structure.