The utility model discloses a fixing fitting and a connection fitting using the same. A supporting member of the fixing fitting is inserted into an end opening of a tubular busbar. The periphery of the supporting member is fixedly provided with contact pieces that can extend and retract in an elastic manner. Each contact piece has an initial position that enables the contact piece to upward or folded in a natural state, and also has a clamping position that enables the contact piece to be placed on the inner wall surface of the tubular busbar through clamping after the supporting member is inserted into the tubular busbar. When the fixing fitting is in use, the contact pieces on the supporting member are in the initial positions before being inserted into the tubular busbar, the supporting member is then inserted into the tubular busbar by being pushed by outside force, and the contact pieces at the periphery of the supporting member are positioned on the inner wall surface of the tubular busbar through clamping through outside force or self deformation, so that the entire fixing fitting is inserted into the end opening of the tubular busbar through clamping assembly. In this way, the connection fitting has the advantages of being convenient to assemble, being simple in structure and occupying less space.