In engineering practice, due to various functional requirements, structures with geometric discontinuities occur widely; in addition, most structures undergo complex multiaxial loads, which drives the development of relevant theories. As a result, to provide reference for structural anti-fatigue design and ensuring their operation safety, the establishment of fatigue lifing methods for notched components under multiaxial loads is critical and indispensable. In this paper, by combining the popular Fatemi-Socie critical plane model with the critical distance theory, a fatigue lifing model for notched structures under multiaxial loads was established, and its effectiveness was verified with the fatigue test data of TC4 stepped shaft specimens. Results show that the proposed model can overcome the conservative estimation problem when performing fatigue lifing based on the stress-strain data of critical points, with all predicted fatigue lives within two-time error bands. Finally, the method was applied to the fatigue life prediction of a turbine compressor disc.