In order to acquire freezing model of the cryopretective solution (NaCl-propylene glycol-water ternary system) for platelet, the melting points (T(f)) of this cryopretective solutions with different solute concentration and different ratio of PG mass to NaCl mass were measured by using a differential scanning calorimeter (DSC), and these experimental data were fitting by computer. An empirical equation was derived which characterized the Tf as a function of the solute concentration and the ratio of PG mass to NaCl mass inside this solution. It was concluded that the equilibrium freezing model for human platelets in this system could be used to instruct platelet cryopreserving techniques.