Objective To investigate gait characteristics of both lower limbs in female patients before and after unilateral total knee arthroplasty (TKA). Methods Based on three-dimensional (3D) motion capture system and independent-sample t test, gait parameters of 10 female patients were compared in both lower limbs and compared with those of 10 healthy subjects before and after TKA. Results The preoperative stance phase, peak adduction angle, adduction-abduction range of motion (ROM) and peak flexion moment of the unoperated knee were significantly higher than those of the operated knee (P<0.05), while postoperative gait parameters were similar in both sides. Compared with the control group, the patients had significantly lower speed and stride length, longer double support time before TKA (P<0.05). Moreover, the operated knee demonstrated significantly lower peak extension and adduction angles, adduction-abduction ROM, peak flexion and abduction moments, higher peak adduction moment, and the unoperated knee revealed significantly lower peak extension angle, higher peak flexion and adduction moments than the control group before TKA (P<0.05). The greater differences of peak knee extension angles and adduction moments of both sides still existed in the two groups after TKA (P<0.05). Conclusions Unilateral TKA could ease pain and reduce gait deviations in both lower limbs of patients. However, there were still gait differences compared with the control group. Patients still suffered deficits in joint function, such as muscle strength and proprioception, and revealed pathological gait and posture. It’s advised that patients should enhance muscle strength of the operated limb, and take gait correction exercises. Female patients should also control walking speed to avoid increasing pressure on the knee after TKA.