Portable DC De-icer can form a controllable direct current on the transmission line by rectifying the 0.4kV or 1kV AC power supply through a silicon controlled rectifier. Due to the resistance property of the transmission line, the direct current passing through will raise the temperature of the transmission line, thereby melting the ice on the line and achieving the de-icing purpose. Meanwhile, by controlling the trigger angle of the silicon controlled rectifier valve, the magnitude of the direct current added to the transmission line can be continuously and precisely adjusted in real time, thereby accurately controlling the temperature of the transmission line and safely and effectively de-icing the line. It is suitable for distribution lines and transmission line ground wires, and can effectively implement safe, fast and convenient de-icing.