In this work, four approaches based oil the UNIFAC model are proposed to predict the azeotropes without any experimental data. The thermodynamic criterion of the four methods is the first derivative of the pressure with respect to the composition which equals Zero at the azeotropic point for a binary system. If the vapor phase of the binary Mixture is considered as an ideal gas, only the UNIFAC model is used; otherwise, the UNIFAC model, Peng-Robinson equation of state (EoS), and one of the Huron-Vidal (HV), Orbey-Sandler modification of Huron-Vidal (HVOS), or modified Huron-Vidal first-order (MHV1) mixing rules are combined to calculate the azeotrope. According to the positive or negative sign of the second derivative of the pressure with respect to the composition, the azeotropic types can be determined. In total, eight binary systems of ethane (R170) + trifluoromethane (R23), pentafluoroethane (R 125) + cyclopropane (RC270), cyclopropane (RC270) + 1,1,1,2-tetrafluoroethane (R134a), pentaffluoroethane (R125) + propane (R290), 1,1,1,2,3,3,3-heptafluoropropane (R227ea) + dimethyl ether (DME, RE170), 1,1,1-trifluoroethane (R143a) + butane (R600), and pentafluoroethane (R125) + isobutane (R600a) were used to verify the methods. With the results of the prediction, the cost and time of experiments can be saved.