In this paper, the liquid-solid equilibrium for the ternary systems composed of 1,2-propanediol, MCl (M=Na, K, Rb, Cs), and H2O were studied at 298.15 and 308.15 K, with the mass fraction of 1,2propanediol ranging from 0 to 0.9. The solubilities, densities, and refractive indices of the saturated systems, and the densities and refractive indices of the unsaturated solutions are reported herein. The solubilities were determined via a titration method using mercury nitrate as the titrant. Refractive index and density data were measured using an Anton Paar RXA170 refractometer and Anton Paar DMA4500 densimeter, respectively. The experimental values of the solubilities and densities of the saturated solutions decreased with increasing 1,2-propanediol concentration, whereas different trends of increase were observed for the refractive indices. The experimental density and refractive index data for the unsaturated solutions increased with increasing 1,2-propanediol to water ratios. Empirical equations have been provided for these properties as a function of concentration. On the basis of the standard deviations, we concluded that the empirical equations could be satisfactorily used to correlate the solubility, density, and refractive index data of the investigated systems. These values will enrich the thermodynamics data for alkali metals in mixed solvents, and lay a foundation for any subsequent work.