Abstract: To investigate the effect of longitudinal uneven wear on small-radius curve rails on the initiation of rolling contact fatigue (RCF) cracks, a three-dimensional rail wear prediction model and an RCF crack initiation prediction model were respectively established based on Archard's material wear theory and damage function theory. By combining a profile iterative update strategy and a damage accumulation method, a prediction method for RCF crack initiation in rails considering three-dimensional longitudinal uneven wear was proposed, and analyzed for U75V quenched steel rails. The study shows that: as the number of vehicle passes increases, the difference in longitudinal wear depth distribution of the outer rail first increases and then gradually decreases with wear development, while the difference in the inner rail's longitudinal wear depth distribution gradually decreases; the short-wavelength irregularities caused by such three-dimensional longitudinal uneven rail wear lead to significant fluctuations in RCF damage distribution, causing the earliest initiation position of longitudinal RCF cracks in rails to change with wear development. The multi-point wheel-rail contact induced by rail head profile changes leads to changes in RCF initiation positions: two main initiation bands form in the outer rail near the regions 23 mm from the gage corner and 30 mm from the rail side, while a single main initiation band forms in the inner rail near the region 11mm outside the rail crown. RCF cracks first initiate within these bands. The predicted RCF crack initiation life considering three-dimensional longitudinal uneven wear is closer to reality. From the early service stage of the rail to approximately 150,000 passes of a single vehicle, the rates of rail wear and damage accumulation are relatively slow. Thereafter, accelerated wear leads to a significant increase in damage accumulation. The cumulative damage values at the longitudinal positions of 108.5 m on the outer rail and 83.25 m on the inner rail first reach the crack initiation threshold of 1, where cracks first initiate in these sections. This research method provides a reference for predicting the initiation positions and service life of longitudinal RCF cracks in small-radius curve rails.