The effects of different Nb content（0

0.3%

0.5%

1%）on microstructure of Cr20 Ni80 electrothermal alloy were analyzed by optical microscope（OM）and electron probe microanalyzer（EPMA）.Tensile properties

microstructure and fracture mechanism of the Cr20Ni80 alloy with different Nb contents were analyzed by tensile testing machine and scanning electron microscope（SEM）.The results show that the equiaxed grains in the Cr20Ni80 alloy are increased with the addition of Nb element

and the dendritic structure is refined with Nb element enriched around the grain boundary.Fracture morphology of the alloy is characterized by plastic fracture at room temperature

and tensile strength and yield strength are increased from 515 MPa and 265 MPa to 572 MPa and 346 MPa with the Nb content increased from 0 to 1%

while elongation of the alloy is decreased from 56.5%to 49%.It is shown that Nb has an negative effect on the room temperature plasticity of the alloy.