Aerospace cylindrical roller bearings often operate under high-speed and heavy-load conditions. Its dynamic behavior has a significant impact on bearing performance. Previous dynamic studies have focused mainly on individual cylindrical roller bearings, neglecting the dynamic performance and mechanical properties within the bearing tester system environment. This paper establishes a dynamic finite element simulation model using ANSYS/LS-DYNA under the operating conditions of a bearing tester. Considering bearing speeds and radial loads, explicit dynamic finite element simulations of cylindrical roller bearings are conducted under bearing tester conditions to study the variation rule of contact stress and vibration acceleration. The feasibility of the simulation is verified through theoretical calculations. The simulation results indicate that bearing speed and radial load have a significant impact on the dynamic characteristics of cylindrical roller bearings. As the bearing speed increases, the mean contact stress and roller vibration acceleration of the rollers and components increase accordingly. The mean equivalent stress in the bearing outer ring’s load-bearing area increases by 21.2%. The maximum equivalent stress increases by 23.3% and the peak vibration acceleration in the Y direction of the outer ring’s bottom load-bearing area increases by 37%. With the increase of radial load, the mean equivalent stress in the bearing outer ring’s load-bearing area rise by 47.2%. The maximum equivalent stress increases by 24.6%. The peak vibration acceleration in the Y direction of the outer ring’s bottom load-bearing area increased by 45%, with the mean vibration acceleration gradually increasing.