Abstract: This study investigates the phase transformation, precipitation behavior, and mechanical properties of titanium microalloyed steel under different cooling processes using a Gleeble-3800 thermal simulator, transmission electron microscopy (TEM), and microhardness testing. The results indicate that after deformation at 900°C, the microhardness of the room-temperature microstructure generally increases with higher cooling rates. However, slow cooling facilitates the γ→α phase transformation, promoting the precipitation of nano-sized carbides. A hardness peak of 260 ± 9.9 HV is observed at a cooling rate of 0.5°C/s due to precipitation strengthening. A two-stage controlled cooling process is subsequently employed: rapid cooling at 20°C/s to the phase transformation start temperature of 635°C, followed by slow cooling at 0.1°C/s, which results in the highest microhardness of 275 ± 11.3 HV and an average precipitate size of 2.55 nm. When the partitioning temperature is set at 700°C, a hardness peak of 260.6 ± 8.1 HV is achieved at 0.5°C/s, with an average precipitate size of 6.73 nm. In contrast, a partitioning temperature of 600°C suppresses ferrite transformation, leading to lower overall hardness in the room-temperature microstructure. For the production of titanium microalloyed high-strength steel using medium-thick plate processes, to fully promote the precipitation of nano-sized carbides and maximize their strengthening effect, the finish cooling temperature during laminar cooling should be controlled close to the phase transformation start temperature. Subsequent cooling rate reduction measures, such as stacking, slow cooling pits, or steam cooling, are recommended. If air cooling is applied after laminar cooling, nano-sized carbides can still contribute to precipitation strengthening, but a higher finish cooling temperature (e.g., 700°C) should be maintained.