A shilly-car includes a main frame module with a rear-wheel tube and a main-frame tube, a front connecting tube and a swing module. A seat cushion is mounted onto a T-shaped structure comprised of the rear-wheel tube and main-frame tube, and two wheels are installed at both ends of the rear-wheel tube respectively. The swing module includes a pedal tube and a swing tube having a bearing sleeve and a bearing. The front connecting tube has an end rotably fixed to the swing tube and the other end fixed with the main-frame tube, and a C-shaped fixed element is installed at an end of the front connecting tube for receiving the bearing sleeve and the bearings, and a fixing shaft is provided for rotably fixing both bearing sleeve and bearing, so that the pedal tube can be stepped by both legs of a rider to move the shilly-car forward.