Abstract: Based upon the results of electrochemical measurement and mathematical analysis,a new method——the Inflexion Tangent Approach——was proposed to analyse the permeation curves of hydrogen.This method has many advantages.It does not have to wait for the stable state of hydrogen permeation and is not so sensitive to experimental conditions. It could be used for armco iron and high-strength steels. Its mathematical treatment is rational and simple. By means of the Inflexion Tangent Approach, the Inflexion Tangent Equation of hydrogen permeation curve has been derived. And the formulas for calculating the diffusion coefficient and the concentration of dissolved hydrogen are respectively.