The usage of pneumatic artificial muscle in rehabilitation robotics has increased in recent years. As locomotion training is proven to be a highly effective approach, a power assisted knee-ankle-foot orthosis (KAFO) with pneumatic artificial muscle is proposed. McKibben pneumatic artificial muscle (MPAM) is chosen in this project due to its ease of fabrication. Design requirement of the prototype are listed, including comfort of the user, safety, and the weight of the prototype. Antagonist configuration is implemented in the prototype with circuitries developed to generate a normal walking gait for the power assisted orthosis which will support the subject. The prototype is tested on a subject and result shows similar gait patterns with actual human gait pattern.