Background Since knee osteoarthrifis (KOA) is one of the common diseases, identification of its associated risk factors is of preventive significance. This investigation was designed to investigate the prevalence of KOA in Taiyuan, and identify the associated risk factors of KOA.Methods A population sample was surveyed of 2188 adults aged from 35 to 64 years, living in 6-story buildings without elevators. The protocol of Asia Pacific League of Associations for Rheumatology (APLAR)Community Oriented Program for Control of Rheumatic Diseases (COPCORD) core questionnaire was implemented. The data on knee pain and KOA were collected and analyzed. Variables such as sex, age, body mass index (BMI), waist circumference (WC), education level, and smoking history, were included in binary logistic regression model for further analysis.Results The prevalence rates of knee pain and KOA were 13.6% and 10.9%, respectively, significantly higher than those in Shantou of south China and similar to those in Beijing of north China. The prevalence of KOA was significantly higher in women than in men (18.3% versus 8.7% and 15.1% versus 6.3%), with a tendency of increase with age. The prevalence was increased more obviously in women after 40 years old and in men after 45 years old. BMI in KOA group was significantly higher than that in non-KOA group. Binary Logistic regression revealed that age, sex, and BMI were significantly associated with KOA, whereas no significant correlation was seen between KOA and other factors such as climbing stairs, WC, time length of occupation service, education level, smoking history and religious belief.Conclusion Geography, age, sex, and BMI might be the risk factors of KOA, but climbing stairs, WC, time length of occupation service, education level, smoking history and religious belief are not correlated with KOA.Prevention of KOA should be initiated before the middle-age, especially in female adults, and weight control is necessary.Other factors might also contribute to the development of KOA,but further study is needed to elucidate the role of these factors.