This study investigated the performance the patients with total hip replacement (THR) and healthy adult whiling crossing obstacles. By using a 3D motion analysis system and force plates, we measured the parameters of: (1) toe-obstacle clearance, (2) heel-obstacle clearance, (3) distance between toe and obstacle before crossing, and (4) between heel and obstacle after crossing. In the healthy adult, the results revealed that except the TD of the trailing leg (p=0.001), other parameters were no significant difference in every crossing condition. Although the THR-patient also showed insignificant different before operation, but in the phase of 2 weeks after the operation, he could only execute the 10 cm crossing condition because of the self-perceived range of motion limitation of the hip surgery, and the performance was unsatisfied. Until the recovery stage in 6 weeks after the operation, the subject could execute all crossing activities, and there was significant difference in toe-obstacle clearance (p=0.006) while the obstacle height changed, but the other parameters did not show difference significant, and the performances were almost near the healthy adult, with a stable crossing pattern. This study was the initial study on THR-patient, we hope that we can understand the recovery stage of these groups, and base on these results to set up better rehabilitation program after operation, and finally prevent fall in daily life.