On the basis of ensuring structural safety, scientific and reasonable excavation of the fatigue strength potential of a platform is of great significance to prolong its service life and improve the economic benefits of offshore oil and gas fields. Through an actual offshore platform case, this study analyzed in depth the key factors influencing the fatigue life of offshore platforms. The results show that the fatigue damage of the structure is often caused by several main contributing waves with periods close to the peak period of the response spectrum. Optimizing the platform azimuth can improve the fatigue life. Increasing the size of local members may not improve the joint fatigue strength. The selection of the wave spectrum and the S-N curve is crucial to the fatigue life results. The identification of these factors provides an important reference for the consideration of platform safety and economy in engineering practice.