The invention relates to the quinuclidine compounds of formula I having quaternary ammonium group, its preparation, and the pharmaceutical composition comprising an effective amount of the compound of formula I. The compound and the composition are used to prevent and treat the diseases by blocking acetylcholine receptor. ##STR00001## Wherein: R.sub.1 is selected from C.sub.1-12 saturated straight-chain alkyl and cycloalkyl; R.sub.2 is selected from C.sub.1-12 saturated straight-chain alkyl or straight-chain alkyl; X is selected from halogen ion, organic and inorganic acid radical.