Silt and fine sand taken from Huanyuankou Yellow River in Zhengzhou and pure water was chosen as three kinds of typical underlying materials, volatile behavior of BETX were studied on these. The study include volatilization dynamic curves of BTEX compounds and mixture and the optimized simulation formulas for them on the base of volatilization kinetics model. The results indicate that, on the same underlying materials, volatility speed of BTEX compounds and mixture is different. On the three underlying materials, volatility speed was pure water, sand and soil in sequence. There existed linear relationships between volatility rate and evapor pressure. Volatile area of underlying surface and pore diffusion flux in the process of volatile are main influence factors for the benzene evaporation.