Corrosion is one of the most typical form of durability degradation of steel bridge and the corrosion morphology takes significant effect on the strain distribution of the structural surface，which has evident effect on the ultra-low cycle fatigue performance of steel plate. In order to investigate the characteristics of steel corrosion morphology as well as the effect of the corrosion on the structural ultra-low cycle fatigue(ULCF) performance, this paper takes the steel kind of Q345 as the study case, conducting 2D and 3D profile measurements on four groups of steel plate samples in different accelerated corrosion conditions. Quantitative analysis on 2D profile data were performed with the methods of surface roughness, fractal dimension, and power spectrum density function, thus discusses the possibility to classify the corrosion morphology. Meanwhile, precise finite element models consisted by hexahedron elements of corroded specimens were established on the basis of 3D profile data, applied by the improved cyclic void growth model (CVGM), those finite element models were conducted to calculate the UCLF lives and discuss the influence of corroded surface morphology. The research results indicate that: the corrosion rates of the artificial acceleration corrosion tests are significantly affected by the thickness of the rust layers. However, the surface roughness, fractal dimension, and power spectrum density function are unable to differentiate the corrosion degree. According to the numerical calculation results, the unevenness of corroded surface is the very important factor on the UCLF performance degradation. Also, the reduction of the cross section, the position on the surface of specimens, and the dimension characters of the critical corruption pits, that contribute a coupling effect on the ULCF life of the corroded steel specimens.