This is a parameter set for the Tersoff potential to investigate the structural properties of Si-O systems. The potential parameters have been determined based on ab initio calculations of small molecules and the experimental data of α-quartz. The structural properties of various silica polymorphs calculated by using the new potential were in good agreement with their experimental data and ab initio calculation results. The radial distribution function and phonon density of states of SiO2 glass generated by MD simulation were in excellent agreement with those of SiO2 glass obtained experimentally.