AIM:To determine the prevalence rate of pterygium in Ningxia region and to explore the risk factors such as age,gender,the urban-rural difference,geographical position,nationality,economic level and demographic factors·METHODS:Totally 3001 residents were selected by cluster randomized sampling in Jinfeng district and Hongsipu town.Ocular exanmination and questionnaire survey were conducted.The prevalence rate and incidence of pterygium were calculated and the related risk factor was analyzed·RESULTS:The prevalence rate of pterygium was 6.16%in Ningxia region and 5.74%in urban,6.49%in rural area,difference between the two groups was not statistically significant(χ2 = 0.717,P=0.397).As for 26-45 age group and more than 66 age group,the prevalence rate in rural area was significantly higher than urban area.No significant difference was found between male(6.30%) and female(6.82%)(χ2=0.269,P=0.604),the same as that between Hui and Han nationality(χ2=1.641,P=0.440)·CONCLUSION: The higher prevalence rate of pterygium in Ningxia is attributed to geographical position and climate condition,but not significantly associated with gender and nationality.Regarding to rural residents,the prevalence rate is higher in aged group.The course of disease is related to the economic level.