Objective To evaluate the clinical value of 3.0 T MRI T2* mapping quantitative analysis for diagnosis of knee osteoarthritis. Methods The study group included forty-six patients (thirty-two males and fourteen females) with knee osteoarthritis, average age was 41.2±15.5 years. Seven normal healthy volunteers attended as control group. All patients and controls underwent T2* mapping imaging based on FLASH (gradient echo) of the multi-echo sequence. T2* value of knee cartilage of each compartment was measured, T2* value of cartilage of normal control group, mild OA group and severe OA group on different knee compartments were compared, respectively. Results T2* mapping imaging could display the different performance between normal adult, mild OA, severe OA knee cartilage. T2* value of bearing surface of normal adult knee cartilage was medial femoral condyle (26.46±2.55), the lateral femoral condyle (26.51±1.21), the medial tibial plateau (23.10±2.19) and the lateral tibial plateau (25.36±3.17), respectively, no significant difference between all parts of them (F=3.72, P>0.05). T2* value of forepart and posterior part of condyle cartilage were (34.36±6.18) and (38.08±7.07), respectively. All cartilage compartments of bearing surface showed significant increase (P<0.05) in T2* value between normal control group, mild OA group and severe OA group. No significant difference (P>0.05) was found between normal group, mild OA group and severe OA group on non-load-bearing surface and the patellar cartilage in T2 * values. Conclusion MRI T2* mapping quantitative analysis may provide early evidence of articular cartilage damage, degeneration, and assess the degree of knee OA.