A flow adjustable waterway switch device is disposed inside a valve body. The valve body is disposed with an inlet connected to the water source and at least two outlets. The waterway switch device has a driving shaft, a setting plate rotated and disposed inside the valve body and a button mechanism. One end of the driving shaft is disposed outside the valve body, and the other end is disposed inside the valve body. The setting plate is rotated by the driving shaft. The flow area of the inlet is changed by the relative rotation of the setting plate and the valve body to adjust the flow. The button mechanism includes a switch plate rotated and disposed inside the valve body, a switch rotor and a restoring spring, the driving shaft is rotated relatively to the switch rotor but not sliding relatively.