The system of CaO-SiO2-P2O5 ternary glass is not only among the major constituents of steelmaking slags in iron and steel industry, but also play a significant role in other industrial process, such as chemical engineering and glass industry. In the present study, the structure of CaO-SiO2-P2O5 ternary glass with varying P2O5 content from 0 to 15 wt pct at a fixed CaO/SiO2 = 1.4 was investigated using molecular dynamics (MD) simulation combined with X-ray photoelectron spectroscopy and Raman spectra techniques. The results indicated that P5+ ions have a higher affinity to Ca2+ ions which are then stripped away from the silicate network with the addition of P2O5, resulting in the formation of Ca-O-P and Si-O-Si linkages. In addition, almost all P5+ ions displayed as $$ {\text{Q}}_{\text{P}}^{0} $$ Q P 0 ( $$ {\text{Q}}_{\text{P}}^{n} $$ Q P n , n is the number of bridging oxygen in one [PO4]-tetrahedra units) and a small fraction of P5+ ions behave as $$ {\text{Q}}_{\text{P}}^{1} $$ Q P 1 (P-O-P) and P-O-Si. The enhanced degree of polymerization can be detected from the increase of $$ {\text{X}}_{\text{Si}}^{3} $$ X Si 3 and $$ X_{\text{P}}^{1} /X_{\text{P}}^{0} $$ X P 1 / X P 0 (mole fraction of $$ {\text{Q}}_{\text{Si}}^{i} $$ Q Si i or $$ {\text{Q}}_{\text{P}}^{i} $$ Q P i ). Furthermore, the ratio of Raman scattering coefficients for $$ Q_{\text{Si}}^{i} /Q_{\text{Si}}^{1} $$ Q Si i / Q Si 1 and $$ Q_{\text{P}}^{i} /Q_{\text{P}}^{1} $$ Q P i / Q P 1 were determined by combining MD simulated result with Raman spectra, which were considered to be suitable to the present study.