The ion transport processes in homo- and heterovalent solid solutions based on the β-PbF2 crystal were studied using the molecular dynamics method. It was shown that the doping of this crystal with strontium fluoride leads to an increase in the mobility of fluorine atoms. The migration of fluorine by the vacancy mechanism explains the increase in the mobility of fluorine atoms in the Pb0.75Sr0.2K0.05F1.95 solid solution crystal.