Objective To overview the characteristic in development and progress of retinopathy of prematurity (ROP). Method Six hundred and thirty eight premature birth infants with birth weight less than 2000 grams born or hospitalized in three hospitals in Guangdong province were examined by indirect ophthalmoscopy as part of ROP screening. 1172 eyes in 586 infants are included. Follow-up has not been completed in 52 infants. The first time of screening was 4 to 6 weeks after birth or 32 weeks corrected for gestational age. Threshold and pre-threshold (type I) disease was treated by laser photo-coagulation within 48 hours. All infants were followed until complete vascularization, natural regress or for more than 1 month after effective therapy. Data regarding incidence of ROP, corrected gestational age and days after birth of ROP onset, corrected gestational age and days after birth of getting treatment, progress pace and prognosis were collected and analyzed by Spearman statistical analyses. ResultsIn 1172 eyes, ROP developed in 118 eyes (10.07%). In 1054 eyes (89.93%) were completed vascularized. Sixty eyes received laser treatment. In ROP infants, the median gestational age was 29.3 weeks and the median corrected gestational age and days after birth when ROP develops were 36.4 weeks and 59.5 days respectively. There was a negative correlation between gestational age and ROP development and treatment timing （R=-0.65,-0.80；P=0.000）.The median interval days from stage 1 to stage 2, from stage 2 to stage 3, and stage 3 to getting treatment were 14.0, 10.5 and 3.0 days respectively. The interval showed a nonnormal distribution and there is statistical difference （H=30.69，P=0.000）.During the follow-up after treatment, the ocular fixation and following reactions were normal. The structure of optic disc, the macula lutea and retina were normal. ConclusionsTiming of ROP development is about 36.4 weeks corrected for gestational age and 37.5 weeks when treated. The interval is shorter when ROP progresses.The prognosis is good for the treatment of aular.