The vapor/liquid phase equilibrium data of sick house syndrome (SHS) materials were measured experimentally. SHS materials are chemical species to which the human body is exposed, such as the volatile organic chemicals emitted from constructing finishes. In this study, acetone(1) + toluene(2) and benzene(1) + m-xylene(2), as two sets of mixed SHS, were selected in the experimental system. These SHS are used as solvents for various chemical processes and finishing materials for residential dwellings, as well as the components contained in interior construction materials. It is very important to identify their vapor phase concentration and diffusion characteristics under atmospheric pressure. The vapor phase equilibrium concentration of the mixed SHS was measured experimentally, the data were correlated with their phase behavior characteristics, and then their nonideal behaviors were predicted by means of calculating their activity coefficients. The NRTLmodel and Wilson equation were employed as the thermodynamic equilibrium prediction model, in which the parameters of the experimental system were optimized in the course of calculation. The vapor phase concentration for each pair of mixed SHS was proposed with the given temperature range.