Since the Mode I fracture of ice materials determines the safety and integrity of ice constructions, this study investigated Mode I fracture behaviorus of strengthened ice materials at Arctic low temperatures. Forty-five three-point bending (TPB) beams, including 12 plain saline water ice (PI) and 33 PVA reinforced saline water ice (PRI), were tested to investigate the mode I fracture behaviors of plain and reinforced ice at low temperatures. The investigated parameters included the low temperature (ranging from −10 °C to −80 °C), ice type (PI and PRI), and mass fraction of fibre (ωf = 0, 1, 2, and 3%), respectively. The failure modes, general P-δ and P-CMOD curves, initial cracking load, double-K fracture toughness, and fracture energy of PI and PRI at low temperatures were revealed. Meanwhile, the effects of temperature and PVA fibre content on fracture behaviors of PI and PRI were also discussed in details. Test results showed that as the temperature decreased from −10 °C to −30 °C, the increments in unstable fracture toughness of PI, PRIA, and PRIB were 414%, 757%, and 250%, respectively. Moreover, the fracture energy of PRI with 3% ωf was 113 times of PRI with 0%. Based on the results and mechanism explanation, three empirical formulae considering the influences of temperature on the unstable fracture toughness of PI, PRIA, and PRIB materials were proposed.