Abstract: Hydrogen concentration has great effects on mechanical properties of titanium alloy. In this article, the method to obtain the distribution of hydrogen in titanium alloy using the CT images of standard object and hydrogenous sample was demonstrated, and the equation for calculation of the hydrogen concentration was derived. The derived equation was validated by Monte Carlo simulation method. The simulated results show that the calculation precision declines with the increase of thickness. The derived equation is suit for thin object. For the thick object, a 3D CT is required. Quantity analysis of hydrogen concentration in titanium alloys using neutron CT is feasible according to this theoretical study.