Ankle-foot orthoses (AFO) were well-used for stroke patients. Our study developed a new 3D printed AFO with the function of Energy Storage. It would be expected to improve the gait of the stroke patients. This study made a 3D printed joint part fixed between the foot plate and shank structure of AFO. The joint part was made of Nylon and inserted a steel plate to increase the strength against the inversion motion of foot. The potential energy from the dorsiflexion of ankle could be saved in the joint part and released in the pre-swing phase of the gait cycle to help walking. Due to the local health insurance policy patients can replace a new AFO every three months. The life of 3D printed AFO which was used in the condition of 2000 steps one day should last at least 3 months. Therefore this study tested the life of 3D printed AFO using the material test machine. The reciprocating motion of 3D printed AFO was limited in the range of 3 degree of plantarflexion and 10 degree of dorsiflexion. The results showed the shank structure broke in the clamping site of the jig after 144000 times of bending. The broken part showed the separating direction was not in the depositing direction of 3D printing path. It means the printing pattern of every layer is also a key issue for the strength of 3D printed object. In the future, this study will check the strength of 3D printed samples with different printing patterns and redesign the shank structure for the better life.