To determine the underlying causes of blindness and low vision, potentially preventable and treatable causes of the students in blind school in Guangzhou. In 2004, students in Guangzhou Blind School were examined, and WHO Prevention of Blindness Program (WHO/ PBL) Eye Examination Record for children with blindness and low vision was used. Of the 177 students (4-33 years, 13.5 average), all were blind or visually impaired severely (visual acuity, V/A, less than 0.1 in the better eye). No light perception, V/A < 0.05 and visually impaired (V/A < 0.1) were 31.1%, 54.2% and 8.5% respectively, others refused to be examined or were mental retard. The causes were retinopathy of premature infant (ROP) (37.9%), optic nerve hypoplasia, Phthisis or cause unknown, retinal degeneration (8.5%), congenital glaucoma (5.1%), congenital macular abnormal (4.5%), retinal detachment (3.9%), congenital cataract (3.9%), microphthalmos (2.8%), corneal disease (2.8%) and other causes. ROP was the most important cause (37.9%), accounting for 57.7% cases in < or =10 years group, 33.9% in < or = 15-year group, 28.6% in < or = 20-year group, 14.3% in older than 20-year group; and 52.7% in no light perception group, 31.3% in V/A < 0.05 group 63.6% in incorporated and mental retard group. 73 cases (41.2%) were with avoidable blindness and visual impairment including ROP, refractive error and amblyopia after cataract surgery, V/A in 14 cases (7.9%) could be improved after treatment. Along with the improvement of health and socio-economic status, ROP become the major causes in children in recent years. Things remained to be done to eliminate childhood blindness.