Prognostics and Health Management (PHM) exerts an essential influence on the spare supply process and the maintenance activities. Discrete Event Logistics Systems (DELS) simulation model facilitates a better understanding of the maintenance and logistics/support systems. Previous DELS models treat the RUL estimation as a one shot event. However, the treatment would be rough to coordinate the logistics and maintenance activities, and the estimated RUL result would not be sufficiently reliable. In this paper, we propose the principle and operational technique of two-step RUL estimation for the DELS simulation model. Two-step RUL estimation starts with the component RUL modeling subject to a continuous accumulation of degradation. The component deterioration is modeled using a time-dependent stochastic process, which combines the linear degradation path with a random effect. Besides, the sequential logics of the DELS simulation model incorporating two-step RUL estimation is exploited in the local behavior study. Finally, the proposed technique is testified with a case study via the DELS simulation implementation, showing that the performance using two-step RUL estimation outperforms traditional one-step RUL estimation.