Abstract: Slow strain rate tests and fatigue crack growth tests were conducted on GH4169 nickel-based alloy under high-temperature (650 ℃), hydrogen-containing environments at varying pressures (1-3 MPa). The effects of total pressure and hydrogen content on the tensile properties, hydrogen embrittlement susceptibility, and fatigue performance of the alloy were investigated. The results indicate that the hydrogen embrittlement susceptibility of GH4169 alloy increased with rising hydrogen content, particularly under higher total pressure (3 MPa). The hydrogen content and total pressure were found to have negligible influence on the mechanical strength of the alloy. However, under high-pressure and high-temperature conditions, hydrogen was observed to reduce the plasticity of the alloy, leading to more pronounced intergranular cracking with increasing hydrogen content. Additionally, the presence of hydrogen was shown to promote carbide decomposition. At a total pressure of 1 MPa, the fatigue life of GH4169 initially increased and then decreased with increasing hydrogen content, while the hydrogen environment exhibited no significant effect on the crack growth rate. In contrast, under total pressures of 2 MPa and 3 MPa, the fatigue life decreased continuously with rising hydrogen content, and the presence of hydrogen was found to accelerate the crack growth rate.