Dorsiflexion and plantarflexion are an important dynamic function by which the ankle-foot prosthesis must simulate the human foot. Dorsiflexion and plantarflexion are essential functions to the walking pattern. However, most ankle-feet prostheses have a notice lack in mimicking the normal gait dorsiflexion and plantarflexion functions. A new carbon fiber ankle-foot prosthesis has been designed and manufactured. Dorsiflexion and plantarflexion tests achieved using a 25 KN tensile test device. The tests have been simulated and analyzed using ANSYS l6 and the results compared with the experimental results. Both test approaches pointed that the new prosthesis satisfy the ISO 10328 requirements that can be classified as multiaxial as it flexed 10 o and 8 o in dorsiflexion and plantarflexion respectively, under testing loading less than 1230 N.