AIM:To discuss the effect of bone hole size in nasal endoscopic dacryocystorhinostomy on the operation results to find the most appropriate size of the bone hole. METHODS:A randomized, single-blind, parallel study. 200 cases of 200 eyes of chronic dacryocystitis for nasal endoscopic dacryocystorhinostomy treatment in Zhuzhou 331 Aier Eye Hospital from 2010-01 to 2010-10 were randomly divided into two groups: A group of 100 eyes: bone hole size was 6mm×6mm (±2mm), B group of 100 eyes: bone hole size was10mm×10mm(±2mm) or more. Surgery was done with corresponding size of the bone hole by grouping, various adverse effects and results of operations were observed postoperatively. RESULTS:In A group, 9 cases of bone thick-walled and 3 cases of bad bone hole location needed to expand the bone hole, 4 cases were lost, 84 cases finally entered the observed cases, including 2 ineffective cases and 82 effective cases. In B group, three cases were lost, and 97 cases finally entered the observed cases, including 3 ineffective cases and 94 effective cases.The two groups had no statistically significant difference in success rate, patients of A group had less postoperative reaction and responded better. CONCLUSION:The bone hole size of 6mm×6mm (±2mm) is appropriate for nasal endoscopic dacryocystorhinostomy to treat chronic dacryocystitis, featured by minimally invasive, less bleeding, less postoperative adverse reactions and no affecting results of operations.