To investigate the prevalence of chronic mountain sickness (CMS) and its predisposing factors in Pamirs plateau and analysis clinical feature and risk factors.Eight hundred and twenty-four individuals in Pamirs plateau were surveyed used Qinghai CMS scoring system. Demographics, BP, SaO2, heart rate and specified symptoms of CMS were recorded, Hb level was estimated.Overall CMS prevalence was 22.08%, including 21.84% mild and 0.24% moderate without severe patient. Gender, nation, age, immigration time, altitude, occupation and accommodation mode were risk factors for CMS (P<0.05 or P<0.01), CMS prevalence was higher than HAPC rate both in male and female (χ2=90.59 and 44.13, P<0.01). Multiple linear regression analysis showed age, BMI, SaO2 and systolic pressure correlated with CMS (P<0.01).Chronic mountain sickness prevalence in Pamirs plateau is rather high but high altitude polycythemia prevalence is low, so the disease type is high altitude deterioration. Work and exercise more reasonable to avoid overtiredness, oxygen inhalation to raise blood oxygen saturation, control blood pressure and resting therapy can improve CMS symptom and decrease prevalence.