NOVELTY - A connection structure between fuel vaporizer (100) and oxidizer (200), which constitute fuel reformer in fuel cell system comprises: fuel vaporizer containing bottom panel having first through-hole formed in it, inner side panel protruded in direction normal to inner frame surface of through-hole, and top panel having second through-hole; and oxidizer containing third through-hole in fluid communication with through-holes, and top portion of inner wall positioned for connection to bottom panel of fuel vaporizer through secondary weld.    USE - As a connection structure between fuel vaporizer and an oxidizer, which constitute a fuel reformer in a fuel cell system (claimed).    ADVANTAGE - The connection structure between an oxidizer and a fuel vaporizer in a fuel reformer exhibits improved integrity and stability. The method exhibits improved welding efficiency, improved integrity and stability during secondary welding process.    DETAILED DESCRIPTION - A connection structure between fuel vaporizer (100) and an oxidizer (200), which constitute a fuel reformer in a fuel cell system, comprises: fuel vaporizer containing bottom panel having first through-hole formed in it, inner side panel protruded in a direction normal to an inner frame surface of the first through-hole, and top panel having second through-hole positioned to be in fluid communication with the first through-hole, where the top panel is also positioned for connection to a top portion of the inner side panel through a primary weld; and oxidizer containing third through-hole to be in fluid communication with the first through-hole and the second through-hole, and top portion of an inner wall positioned for connection to the bottom panel of the fuel vaporizer through a secondary weld. An INDEPENDENT CLAIM is included for connecting a fuel vaporizer and an oxidizer of a fuel reformer in a fuel cell system, involving forming a fuel vaporizer; and forming an oxidizer connected to the fuel vaporizer, where the step of forming the fuel vaporizer includes forming through-holes in a bottom panel and a top panel, forming an inner side panel protruding in a direction normal to a frame of the bottom panel through-hole, and welding a top portion of the inner side panel to the frame of the top panel through-hole, and the step of forming the oxidizer includes welding a top portion of an inner wall of the oxidizer to a bottom surface of the frame of the bottom panel through-hole.    DESCRIPTION OF DRAWING(S) - The figure shows a view of a fuel vaporizer and an evaporator in a general fuel reformer.    Fuel vaporizer (100)    Oxidizer (200)    Fuel reformer (1000)