Objectives. To determine the difference in efficacy between distal and proximal acupoints in treating knee osteoarthritis. Design. Ninety-two eligible participants were randomly assigned into three groups: distal acupoint treatment group (DG), proximal acupoint treatment group (PG), and sham acupuncture control group (SG). Primary and secondary outcomes were compared before and after the intervention. Interventions. A single acupuncture treatment was applied at Quchi (LI11), Shaohai (HT3), and Tianjing (TE10) in DG participants; Yanglingquan (GB34), Yinlingquan (SP9), and Heding (EX-LE2) in PG participants; and Zhongwan (CV12) and Liangmen (ST21) in SG participants. Main outcome measures. The visual analog scale (VAS) and active and passive knee range of motion (ROM) were used primarily to evaluate the treatment efficacy. The radial pulse diagnosis was used as a secondary outcome measure to determine the changes in the spectral energy of the radial pulses. Results. The three groups had significant pain reduction after acupuncture ( p < 0.05 ). DG had the greatest difference in pre- and post-VAS scores. Compared with the control group, significant improvement was observed in DG active and passive ROM and in PG passive ROM ( p < 0.05 ). The high-frequency spectral energy of the left chi pulse in PG was significantly decreased, while the low-frequency spectral energy of the left cun pulse in PG and the left guan pulse in DG were significantly increased after acupuncture. Conclusions. Distal acupoints provide better pain relief and improve ROM than proximal acupoints in treating knee osteoarthritis. Significant changes in spectral energy were observed in the left cun, guan, and chi pulses, indicating pain relief and blood flow improvement after acupuncture.