This paper describes studies, using a metallurgical microscope, on metallography, microstructure and technology of the iron and steel artifacts excavated from Wandu Mountain city of Gaogouli, and sheds light on the level of development In the metalwork Industry of Gaosouli and on steel and iron techniques used during the Wei, Jin, Southern and Northern Dynasties. The results have been compared with past research on Gaogouli iron objects and show that technologies used by craftsman include: pouring liquid pig iron on edge of iron object (Chinese name: Sheng Tie Lin Kou ), pig iron decarbornization and annealing after casting to obtain steel and malleable cast iron, steel and folding of steel and wrought iron together to form composite artifacts. The arrowhead 03 JWN2T105(2):12 is the earliest example of Sheng Tie Lin Kou technology so far, and therefore the skill can be dated at least as far back as the Wei, Jin, Southern and Northern Dynasties. This discovery suggests that the technique existed about 1000 years earlier than recorded in literature of the Ming Dynasty, and over 600 years earlier than report for a Song Dynasty object. The invention of the technique could be even earlier. This discovery is crucial to understanding the development of steel and iron technology from Han Dynasty to Wei, Jin, Southern and Northern Dynasties.