Objective To evaluate the effects of oral undenatured collagen type Ⅱ on rehabilitation of knee osteoarthritis. Methods Sixteen patients with levelⅠand Ⅱ knee osteoarthritis (KOA) were recruited in this study. The WOMAC questionnaire was used to measure the symptoms of knee joint in patients. The KneeKG 3D evaluation system was used to measure the kinematics characteristics of the knee joints. The pair t-test was applied to analyze the differences in knee kinematics after taking undenatured collagen type Ⅱ for 3 months. Results After taking undenatured collagen type Ⅱ, the patient’s feeling of knee joint pain, stiffness, and the difficulty of daily life was reduced. In addition, the knee flexion angle increased from 51.8°±15.2° to 58.4°±10.7° (P<0.05), and the knee varus angle decreased to 2.1°±4.8°. The improvement rate of knee varus was 82%. Conclusions Taking undenatured collagen type Ⅱ for 3 months could play a role in rehabilitation for patients with early KOA. The knee range of motion was close to the level of healthy elderly people, thus improving the symptoms of knee varus.