In practice, factors such as the assembly process of compressor shaft end connection structures, surface quality of connecting components, and operational loads exhibit significant uncertainties, which can lead to degradation of the shaft end fastening force. To address this issue, the life cycle of the shaft end fastening force was divided into three sequential stages: pre-tensioning, static holding and service operation. A prediction model of the fastening force during the whole life course of shaft end connecting structure was developed and validated using experimental and simulation data. Based on this, a reliability model for compressor shaft end fastening was established to enable quantitative reliability assessment. The results indicate that the proposed fastening force prediction model achieves high accuracy, with errors within ±10%. Under 95% reliability conditions, the critical  fastening force required to prevent loosening, as evaluated by the reliability model, is 36.69 kN, satisfying the specified reliability requirements.