To further enhance low-temperature toughness and clarify the low-temperature fracture failure mechanisms of titanium alloys, a TC4-0.55Fe alloy was prepared by micro-alloying with Fe, and its impact performance and fracture behavior were systematically investigated over the temperature range 20 ℃ to –196 ℃. The alloy exhibits a Charpy impact toughness of 66.8 J·cm^–2 at 20 ℃, which remains unchanged as the temperature drops to –20 ℃. When the temperature drops to –70 ℃, the low-temperature toughness decreases to 46.8 J ·cm^–2. When the temperature drops to –196 ℃, the toughness still retains 25.1 J·cm^–2, which is 23.8% higher than that of TC4 alloy. SEM image of fracture confirms that –196 ℃ is still above ductile-brittle transition temperature. of the alloy EBSD characterization reveals abundant deformation twinning in the vicinity of the crack at all test temperatures, with twin density increasing markedly as temperature decreases. The outstanding impact toughness of the TC4-0.55Fe alloy is attributed to the synergistic effects of fine-grain strengthening, the dispersion of fine acicular α_s precipitates within the β matrix, and a significant increase in twin density at low temperature, which jointly promote crack-path deflection and significantly enhance resistance to fracture.