[Objective] To analyze the clinical curative effect of 20G and 23G vitrectomy for posterior segment intraocular foreign bodies,to explore the differences of their efficacy and safety.[Methods] This was a retrospective case study.Select 71 patients (71 eyes) who suffered from posterior segment intraocular foreign bodies and underwent different ways of vitrectomy,according to the way of vitrectomy,the patients were enrolled into 20G vitrectomy group (20G group,37 patients,37 eyes) and 23G vitrectomy group (23G group,34 patients,34 eyes).All patients were given wound suture,and patients complicated traumatic cataract should underwent cataract surgery;then were given 20G/23G vitrectomy and extraction of intraction foreign bodies,and (or) be given retinal laser photocoagulation,cryocoagulation,and endotamponade during the procedure.Extraction of intraction foreign bodies and the location of retinal,surgical time,postoperative inflammation and stimulus syndrome,length of hospital stay,the best corrected acuity (BCVA) and other complications after surgery were registered.Minimum follow-up was 6 months.[Results] The rate of extraction of intraction foreign bodies and early retinal reattachment rate were 100％ of the two groups.Comparing the complications after surgery between the two groups,the differences had no statistical significance (all P ＞ 0.05) except the incidence of postoperative ocular hypotenison.The significant difference was found in the comparison of surgical time,average hospitalizcd days,postoperative inflammation score and stimulus syndrome between the two groups,and there were significant differences when the vision distribution before and after surgery in two groups were self-compared (P ＜ 0.05).At lastest follow up,the differences had no statistical significance when comparing the cases of unplanned surgical reoperation,the location of retinal and the vision distribution between the two groups (P ＞ 0.05).[Conclusion] 20G and 23G vitrectomy are both safely and effectively performed in patients with posterior segment intraocular foreign bodies,the efficacy and safety of them are comparable.There is higher incidence of postoperative ocular hypotension in 23G group,and it has an ascendant than 20G group in shorter surgical time and length of hospital stay,lighter postoperative inflamnation and stimulus syndrome.