<p>Maintaining good lubrication conditions is crucial for preventing failure modes such as contact fatigue and wear in rolling bearings, which has a significant impact on the bearing s service life. In this study, a dynamic model of rolling bearings is developed that considers the role of the combined load and variations in working contact angle during bearing operation. The Hamrock-Dowson theory is utilized to construct a fully-film lubrication model. We employ a Box-Behnken design (BBD) to sample the random variables of the rolling bearing and obtain the corresponding film thickness ratio. Furthermore, a limit state function for the failure of full-film lubrication of rolling bearings is established based on the stress-strength interference model. A reliability assessment method is proposed that combines response surface method (RSM) with fourth moment method (FMM), providing a comprehensive analysis and optimization design of the full-film lubrication state for both the inner and outer rings of the bearing. Finally, a reliability model of angular contact ball bearings 7209 is established as an example, and Monte Carlo simulation (MCS) is conducted to verify the proposed method. The results demonstrate that the established comprehensive reliability assessment method of rolling bearings with full-film lubrication and the MCS results differ by no more than 0.05 % and the lubricated reliability of optimized bearing has improved by 4.93 %. This indicates that the proposed method has a high degree of computational precision.</p>