A Monte Carlo Simulation (MCS) approach is developed to estimate the system reliability for a multistate manufacturing network (MMN) with joint buffers. System reliability indicates the probability that all workstations provide sufficient capacity to satisfy a specified demand and buffers possess adequate storage. The joint buffers with finite storage are modeled into an MMN. An MCS algorithm is proposed to generate the capacity state and to check the storage usage of buffers to evaluate whether the demand can be satisfied or not. System reliability of the MMN is estimated through simulation. A practical example of footwear manufacturing system shows that system reliability is overestimated when buffer storage is assumed to be infinite.