TIG arc additive manufacturing forming tests were carried out on Q235 A low carbon steel substrate using ER316L stainless steel welding wire. Heat treatment at 1 000 ℃and 1 200 ℃ was performed to study the effect of heat treatment temperature on the microstructure and properties of the parts manufactured by the additive manufacturing. The results has shown that the sample without heat treatment was expected to be austenite +dendritic ferrite +M,23,C,6,. Heat treatment can remelt the M,23,C,6,. And the quality of the M,23,C,6, decreased with the increase of temperature,which resulted in a decrease in the hardness of sample. The ferrite was gradually transformed into austenite during the heat treatment,and its morphology changed significantly:the ferrite exhibited a strip-like structure with the heat treatment at 1 000 ℃,and exhibited a spot-like structure with the heat treatment at 1200 ℃. The tensile strength of sample reached the highest after heat treatment at 1 000 ° C,and its microstructure was austenite strip ferrite +a small amount of M,23,C,6,. After heat treatment at 1 200 ℃,the microstructure of sample mainly consisted of austenite structure,a small amount of ferrite and M,23,C,6,. And the tensile strength came to the lowest.