Objective To compare the walking abilities of an unilateral transfemoral amputee with four different prosthetic knee joints, to provide a reference for clinical prosthetic prescription. Methods An unilateral transfemoral amputee was asked to wear four kinds of pros-thetic knee joints, mechanical four-bar, pneumatic four-bar, hydraulic and intelligent prosthetic knee joints, and evaluated with Timed Up and Go Test, indoor 6-Minute Walk Test, Static Stand Balance Test and a 1000-meter Outdoor Walking Ability Test, wearing Intelligent De-vice for Energy Expenditure and Activity. Results The amputee consumed the least energy and walked the fastest with intelligent prosthetic knee joint. Conclusion There are some difference in walking ability with different prosthetic knee joints.