Abstract: Background: A wide variety of dry materials are used to construct and furnish residential and commercial buildings. It is very important to predict emission characteristics of Volatile Organic Compounds (VOCSs) from building materials. So, Bodalal had provided the mathematical model of VOCS physical emission process, the diffusion and partition coefficients of VOCSs are obtained by the method of drawing, but this method can only obtain fuzzy and imprecise solution. It is necessary to design a new method to solve the model. Materials and Methods: In this study, on the basis of the data of the experiment and the function extreme value theory, diffusion and partition coefficients function is constructed, the function extreme value is calculated by the Extremum-Search Method. Results: So that, a new method for calculation of the internal diffusion coefficient (D) and partition coefficient (ke) of VOCSs is given for dry building materials. Conclusion: The method to calculate the diffusion and partition coefficients of VOCSs is very accurate and practical and the algorithm can be realized easily by the computer program. The VOCS diffusion process can be known accurately, it is significant to reduce indoor pollution.