Based on the cloud computing platform, this paper constructs an analytical model for the indoor diffusion process of volatile organic compounds (VOCs) in building decoration materials. The model considers key parameters such as diffusion concentration, diffusion coefficient, and closed chamber background value, and validates the model through practical examples. The results show that the VOC diffusion law obtained by the proposed model and the numerical simulation calculation model is basically the same, and the calculation time of the proposed model is shorter. The VOCs in indoor building materials mainly undergo two stages of diffusion mass transfer and convective mass transfer, and finally diffuse into the space of the closed chamber. In the early and middle stages of VOC diffusion, the environmental concentration in the closed chamber changes drastically. In the late stage of diffusion, in the closed chamber, the environmental concentration gradually reaches equilibrium, and the mass transfer characteristics of the VOC are basically unaffected by the area of the closed chamber and the air flow rate.