Abstract: To get the adsorption data of low-volatile organic compounds,a method for estimating the adsorption isotherm of low concentration and low-volatile organics was proposed based on the Langmuir equation.The desorption activation energy was calculated by a modified temperature program desorption(TPD) model,which is much closer to the intrinsic value,and then the Langmuir equilibrium constant B was obtained.In combination with sorbent characterization results,it was easy to estimate the saturated adsorption capacity.The adsorption isotherm of low concentration naphthalene on SBA-15 was estimated.The desorption activation energy,balance constant,and saturated adsorption capacity are 58.37 kJ·mol^-1,0.01149 Pa^-1 and 55.11 mg·g^-1,respectively.The calculated values are in good agreement with experimental results,and the relative error is about 5%.