Method of fabricating a direct-heated cathode structure comprising prepunching process wherein fixing segments are inserted to slot in the ceramic base and bended about 45, and finish punching process wherein upper end of prepunched fixing segments are pressed over the ceramic base. Direct-heated cathode structure comprising supporting bars with a supporting protuberance at their upper end and a barricade at their middle to prevent deformation during welding of springs and to confine affection of buckling during electric resistance welding of conductive tape respectively.