A hose clamp for clamping a pipe comprises a metal belt having a first edge and a second edge adapted for being overlapped defining a receiving cavity therein for clamping a pipe with a predetermined diameter, a positioning arrangement comprising a positioning head extended from said first edge of said metal belt, and a positioning head holder provided on said second edge at a corresponding place for receiving said positioning head, so as to guide said first edge and said second edge together in position; and a fastening arrangement comprising at least a welding arrangement comprising a first welding element provided on said first edge and a second welding element provided on said second edge at a corresponding place for being welded with said first welding point, so as to fasten said first edge and said second edge together.