Structural properties of the pure water and halogen solutions at high temperatures and pressures are studied by using the molecular dynamics simulations and quantum molecular simulations. The related characters are calculated as functions of temperature and pressure. The results show that the hydrogen bonded networks become looser as temperature increases,with the collapse of the traditional tetrahedral structure. It is similar to the concentration-dependent collapse in the Na Cl solutions. However, adding other halogen elements has no further effects on the already weakly bonded water molecules.At the phase changing points, the process of hydration is evident for the bigger ions, so that the bigger the ion is, the smaller a cluster is formed. Structural properties of the pure water and halogen solutions at high temperatures and pressures are studied by using the molecular dynamics simulations and quantum molecular simulations. The related characters are calculated as functions of temperature and pressure. The results show that the hydrogen bonded networks become looser as However, adding other halogen elements has no further effects on the already-already weakly bonded water molecules. At the phase changing points , the process of hydration is evident for the bigger ions, so that the bigger the ion is, the smaller a cluster is formed.