Abstract: This paper presents an improved method for measuring emission characteristics of volatile organic compounds (VOCs) of building materials, including the average initial concentration and the partition coefficient, and the model of convective mass transfer coefficient. By applying this method, the convective mass transfer coefficient and the VOCs emission characteristics of some building materials including plywood, particle board, PVC flooring and carpet are obtained. It is concluded that this model can improve the accuracy of the partition coefficient and the convective mass transfer coefficient with a shorter experiment time and larger volume ratio of the small airtight chamber and testing materials.