ABSTRACT Leaf springs, as vital suspension components in trucks, endure various forces such as torsion, compression, tension and impact, rendering them highly susceptible to fatigue and fracture risks, thereby posing a significant threat to vehicle safety. During the production process of leaf springs, surface decarburisation can easily occur, leading to the formation of numerous surface rolling defects. These defects exert varying influences on the initiation of fatigue crack. This study investigates the influence of various forms of rolling defects caused by decarburisation on fatigue crack initiation in 50CrMnMoNbAT leaf spring through experimental and numerical analysis of fatigue fracture behaviour. The results indicate that fracture locations in the leaf springs are predominantly concentrated approximately 297 mm and 698 mm from the ends. Furthermore, the occurrence of surface decarburisation during the rolling process engenders a significant number of surface rolling defects. Surface defects in leaf springs can be categorised into three forms: Parallel defect, Parcel defect and Occlusal defect. In terms of defect propagation rate, rolling defects on the concave surface are most prone to initiate fatigue cracks, with Occlusal defects exhibiting the highest likelihood of developing internal cracks and the fastest crack propagation rate.