AIM:To discover the cause of dislocation of nucleus into vitreous vacuum in phacoemulsification and proper management for these conditions. METHODS:Totally 7526 cases with dislocation of nucleus in phacoemulsification were reviewed in 5 years. RESULTS:Seven patients had severe dislocation of nucleus.2 cases suffered pars plana vitreoctomy(PPV) and 5 cases had mature or over mature cataract.When dislocation happened,3 patients was immediately performed PPV combined with intraocular lens(IOL) implantation,1 patient was implanted PMMA IOL without taking out of nucleus,1 patient suffered retinal detachment after 2 weeks,and 2 patients could not be further proceed for poor condition. CONCLUSION:The vitreous state(high fluidity) is the most common cause for dislocation of nucleus in phacoemulsification.PPV is a proper method for these patients.