The purpose of the present paper is to investigate an estimation procedure of the ultimate strength of reticular domes with geometrical imperfections and under non-uniform loading. The elastic plastic buckling stress has been summarized to evaluate the buckling load as a function of a normalized slenderness ratio with reduction factor α. According to several numerical comparisons, the effects of the imperfection are considerable in case of pin supported dome more than roller supported one. Even though these effects can not be neglected, the proposed procedure is proved to give a beneficial estimation of the buckling load with reduction factor α.