1～3℃。Freeze-drying microscopy (FDM) was used to investigate the critical temperature (Tcr) of sublimation interface during freeze-drying of binary aqueous solutions, and differential scanning calorimetry (DSC) was used to investigate the eutectic melting temperature (Tem) and the glass transition temperature of the maximally freeze concentrated solution (T′g). The experimental results showed that if a solute crystallized from solution during freezing step, the critical temperature was the eutectic melting temperature, or else a meltback would occur. If the solute remained amorphous during the freezing process, the critical temperature was the collapse temperature, or else the amorphous phase would undergo viscous flow. For 5% Sucrose, 10% glucose, 10% maltose, 10% PVP binary aqueous solutions, the microcollapse temperature (Tmc) and the collapse temperature (Tc) differed by less than 2℃, and Tmc was 1～3℃ above T′g.