To address the poor meshing performance of helical cylindrical gears under variable center distances in high-speed rolling mills, this study establishes a finite element meshing model in Abaqus, considering gear meshing misalignment. Under typical operating conditions, simulation analyses of gear tooth contact are carried out to study the influence of center distance variation on key meshing performance parameters. Based on these results, comprehensive tooth surface modifications are proposed, including linear and crowning reliefs along the tooth lead direction and tip reliefs along the profile direction. A comparative analysis of gear meshing performance before and after modification is then performed. The results show that, prior to modification, the tooth surface exhibits significant load bias. Increases in center distance lead to a considerable decrease in contact ratio and contact area percentage, along with notable increases in maximum contact stress, maximum root bending stress, and the peak-to-peak transmission error-resulting in a substantial decline in overall meshing performance. Following surface optimization, load bias is significantly reduced, and improvements are observed across all key indicators, including reductions in maximum contact stress, bending stress and transmission error. The optimized gear surface exhibit enhanced adaptability to center distance variations, leading to a marked improvement in meshing performance.