Abstract: Initial geometrical imperfections affect the stability of a suspending-dome obviously. To apply the proper initial geometrical imperfections to a suspen-dome through a random imperfection mode method during calculating structural stability is the main purpose of this paper. Firstly, the overall stability of a rib type 2 suspen-dome, considering different initial geometrical imperfections, was analysed through the consistent imperfection mode method. Then, how to select the variance value in the random imperfection mode method was discussed, and at the same time, the overall stability of the rib 2 type suspen-dome considering 210 types of initial geometrical imperfections were analysed through the random imperfection mode method, the magnitude of the imperfection considered is all 1/300 span. Results show that the structural stability is sensitive to initial geometrical imperfections, the stability factor considering initial geometrical imperfections is about fifty percent of perfect structure. When the consistent imperfection mode method is selected during calculating structural stability, the structural stability is probable to estimate by some times of calculations considering different initial geometrical imperfection distributions. Thus it is proposed that the random imperfection mode method could be adopted to calculate structural stability according to the initial geometrical imperfections when the structure has a large span and a complicated form.