The coordination structure of the quaternary mold fluxes CaO-B2O3-SiO2-TiO2 is invested by means of molecular dynamics simulation, and then the regularity of the changes for the variety of TiO2 content is concluded. The results show that there are only three-coordinate triangular body and four-coordinated tetrahedron of boron, and it is mainly the form of six-coordinated octahedral between Ti and O in the slag. With the increasing of TiO2 content, microstructure ligands form of Si, B and Ti will change significantly, converting to the direction of four-coordinate structure, three-coordinate structure and five-coordinate structure respectively.