An attentive observation and quantitative analysis of {259}f martensitic surface relief in an Fe-23Ni-0. 55C alloy are made by means of an atomic force microscope (AFM), and different martensitic variants’ shear angles are determined in this paper. The experiments show that {259}f martensitic surface relief exhibits regular shape in many cases, which is in agreement with the prediction of invariant plane strain (IPS). Generally, {259}f martensitic surface relief appears to be “ N”-shaped, but it is tent-shaped in the case of zigzag-shaped martensite. The compressed deformation of parent phase diminishes the surface relief in size but with little change of its relief angle. {259}f martensitic surface relief, large or small, has approximately the same relief angles, exhibiting a good “self-similar fractal”. The determined values of different {259}f martensitic variants’ shear angles are in fine agreement with the prediction of Wechsler-Liberman-Read (W-L-R) theory, with only a slight difference of less th An attentive observation and quantitative analysis of {259} f martensitic surface relief in an Fe-23Ni-0. 55C alloy are made by means of an atomic force microscope (AFM), and different martensitic variants’ shear angles are determined in this paper. The experiments show that {259} f martensitic surface relief exhibits regular shape in many cases, which is in agreement with the prediction of invariant plane strain (IPS). Generally, {259} f martensitic surface relief appears to be “N ” -shaped, but it is tent-shaped in the case of zigzag-shaped martensite. The compressed deformation of parent phase diminishes the surface relief in size but with little change of its relief angle. {259} f martensitic surface relief, large or small , has approximately the same relief angles, exhibiting a good “self-similar fractal”. The determined values ​​of different {259} f martensitic variants’ shear angles are in fine agreement with the prediction of Wechsler-Liberman-Read (WLR) theory, with only a slight difference of less th