Abstract: We conduct a detailed simulation study on the high-temperature thermochemical nonequilibrium phenomena of hypersonic nitrogen flows over blunt bodies, double cone, and backward-facing steps, based on a high-fidelity vibrational state-to-state model. Comparisons with experimental data validate the accuracy and reliability of the StS model in predicting wave structures, wall heat flux, and pressure distributions. Furthermore, correlating macroscopic temperature distributions and species evolution with microscopic vibrational energy level distributions and thermochemical energy source terms reveals the dominant mechanisms of thermochemical nonequilibrium and their evolutionary dynamics across different flow regions. In the shock compression-dominated region, the molecular energy level distribution is mainly controlled by the competition between vibrational excitation and dissociation reactions. Behind the shock wave, the vibrational distribution function gradually transits from an overpopulation of high energy levels driven by vibrational excitation to an underpopulation caused by dissociation reactions. In the near-wall region, wall cooling causes a decrease in translational temperature, and atomic recombination reactions gradually dominate, continuously injecting energy into higher vibrational energy levels, resulting in a pronounced plateau-like overpopulation of vibrational energy levels, which macroscopically manifests as a non-monotonic variation in vibrational temperature. In the expansion-dominated region, the decrease in flow density significantly reduces vibrational relaxation and chemical reaction rates, leading to a microscopic vibrational energy level distribution that remains similar to the pre-expansion distribution, and ultimately manifests as the freezing of vibrational temperature on a macroscopic scale. The detailed state-to-state simulation results reveal the relationship between microscopic energy level evolution and macroscopic flow structures in compression and expansion-dominated regions, providing a basis for the physical modeling of high-temperature nonequilibrium flows.