The single component model and the multicomponent model of the effectiveness factor zeta(d) of the poisoned catalyst have been proposed and solved by the orthogonal collocation method. The center equilibrium dead zone was founded in catalyst pellets. The calculated values zeta(d) were respectively 0.1229approximately0.2907, 0.1298approximately0.2445 and 0.0690approximately0.2155 for No. 1, No. 2 and No. 3 catalyst. The average of the absolute values of the relative deviations between the experimental values and the calculated values by model for zeta(d) was less than 11 per cent. The models can be used to calculate the effectiveness factor of the poisoned catalyst.