The ab-initio molecular dynamics simulations were conducted to etude the microscopic atomic and electronic structures of Co54Ta11B35 bulk metallic glasses in the surface composition. The structure properties such as partial pair correlation function, bond pairs and Voronoi tessellation analysis were analyzed. Then the atomic charge and the density of states are also characterized. The degree of local ordering for B is illustrated to decrease in the surface. A liquid-phase B-center cluster was found to increase during annealing. The Co-center distorted icosahedron cluster transformed to the perfect one which could be a signature of surface crystallization. But this crystallization did not change the electronic structure of Co54Ta11B35 alloy obviously. •We simulated the surface structure of a new bulk metallic glass.•The two main elements Co and B showed different tendency during the anneal.•The distorted icosahedron cluster transformed to the perfect one which could be a signature of surface crystallization.•A liquid-phase B-centre cluster was found to increase during the anneal.•This variation of atomic structure do not change the electronic structure of this material.