An optimized connection structure for a metal pipe fitting and an implementing method thereof. The structure includes: pipe fittings (1), multifunctional plugs (2, 20) arranged in the inner holes of the tail ends of the pipe fittings (1), and a connecting member (3) connecting the pipe fittings (1). The pipe fittings (1) are provided with radial through holes (13) about the periphery of the connecting part. The multifunctional plugs (2, 20) include: a plugging body (21) at the tail end, a groove (23) in the middle, and a large and a small positioning steps (22, 24) at the top end, the positioning steps being connected with each other. The connecting member (3) may be of a cast/forged composite structure, wherein an inner layer and an outer layer of metal rings (42, 41) and a plurality of radial and axial metal posts (43, 44) connected therewith are formed in a casting/forging mold, and forge-welded parts of the pipe fittings (1) and of the plugs (2, 20) subjected to casting/forging are three dimensionally fit together and forged into an integral structure, thus allowing the various pipe fittings (1) of a bicycle frame and of the fork thereof to be connected in a strong but pliable manner.