This dissertation presents a design and fabrication of a wheeled mobile robot with variable wheelbase and track. This robot has the function of electric wheelchair. When the robot works indoors, it has to reduce the wheelbase and track in order to avoid an obstacle. And slow down the speed of the wheeled mobile robot. When the robot works outdoors, the wheeled mobile robot transforms into high-speed mode. The wheelbase and track of the wheeled mobile robot is increased, and the center of gravity is lower than low-speed mode. It has the advantage of stability, and makes the rider comfortable.