Abstract: According to the essential characteristic of high carbon medium manganese austenitic steel and medium carbon quenched and tempered cast steel,their weldability was theoretically analyzed and their welding procedure tests were made with gas metal arc welding. The test comparison was made under a stainless steel welding wire with different shielding gas,different preheating process,different welding methods of multi-layer and multi-pass and different welding heat input. Macrostructure,microstructure and mechanical properties of welded joints were studied by means of the optical microscopy and mechanical properties measuring equipments. The result showed that high carbon medium manganese austenitic steel and medium carbon quenched and tempered cast steel with poor weldability could obtain excellent welded joint with mixed gas of 95% Ar + 5% O₂,low welding heat input,welding methods of multi-layer and multi-pass and no preheating,meanwhile,by which the cost was reduced and the efficiency was improved.