With the development of renewable energy, hydrogen energy is paid more and more attention. Hydrogen is an excellent energy carrier, but it is difficult to store and transport because of its special properties. Hydrogen blended with nature gas is considered to be one of best transition solutions to solve the problem of large-scale hydrogen transportation. But hydrogen embrittlement occurs when the pipeline steel used to transport natural gas is exposed to hydrogen environment. Referencing to ASME B31.12, X42 pipeline steel is selected as the research object in this paper. And the mechanical properties of X42 were tested by electrochemical hydrogen charging, slow strain rate tensile (SSRT) test and fatigue crack growth (FCG) test combined with thermal desorption spectroscopy (TDS) and SEM. Hydrogen adsorption properties of X42 pipeline steel at room temperature was measured by TDS. SSRT test showed that the strength of X42 strengthened slightly in electrochemical hydrogen charging environment, but the plasticity decreased significantly, and the embrittlement degree of materials increased with the elevated current density. FCG test showed that the presence of hydrogen will accelerate the crack growth rate and reduce the fatigue life of materials. SEM images of tensile and fatigue specimens showed that hydrogen transforms the fracture mode from ductile fracture to cleavage fracture.