Abstract: The microstructure and properties of weld metal with three amount of carbon were investigated by means of optical microscopy,scanning electron microscopy with EDS and transmission electron microscopy.The results indicate that the dominant microstructure changes from the acicular ferrite to the lath martensite and the width of martensite lath is much more finer with the increase of carbon content.In addition,with increasing carbon content in weld metal,the Mn and Ni segregations become worse,the hardness and strength of weld metal increase,and the hardness differences of prior δ-ferrite columnar boundary region and prior δ-ferrite columnar core are increased.