The present invention is provided with a waterless detection method and a waterless detection device of a boiler iron and an iron applied with the device thereof. The present invention is applied with a normal close thermostat of the constant temperature boiler and a control device, a signal line between the thermostat of the traditional boiler iron and the control device to send the off and on information of the thermostat to the control device. The control device can judge the presence of the water in the water tank according to the empiric value of the actual heating system, preventing the pump from damage due to empty pumped. Compared to the traditional iron with other hardware detection device, the present invention costs lower with simple manufactory. And It saves more space for other component of the iron as well.