As a critical load-bearing component of railway vehicles, the bogie's structural integrity significantly influences the operational safety and service longevity of rolling stock. The fatigue crack growth behavior of Q355NHC bogie steel under varying experimental conditions (sampling direction and stress ratio) was systematically investigated, complemented by comprehensive microstructural characterization and fracture surface analysis. The experimental results reveal that the material exhibits minimal sensitivity to variations in sampling direction regarding crack propagation rates. However, a pronounced stress ratio dependence is observed, where the fatigue crack growth rate demonstrates significant acceleration with increasing stress ratio. Building upon the Paris law framework, we proposed an enhanced fatigue crack growth normalization (FCGN) model incorporating stress ratio effects through parameter normalization. Validation using experimental data demonstrates the FCGN model's superior predictive accuracy in characterizing stress ratio-dependent crack propagation behavior for Q355NHC steel. The developed methodology provides valuable technical insights for fatigue life assessment and damage-tolerant design of bogie components in engineering applications.