To evaluate and optimize the performance of the serial production lines with multiple rework loops, according to the principles of quality management and lean production, a novel inspection mechanism, "Instant Checking", different from the traditional ones, was introduced in this paper. The PSM problems to the systems with multiple machines and buffers were investigated. Based on the probability theory and the Markov chain, a dynamic probability transition matrix was built to disclose the relationships between the production performance (WIP: work-in-process inventory and PR: production rate) and the status of machines and buffers. Further, the transient analysis on the machines and buffers was conducted with iterative computation. The results of the analysis show the feasibility to improve the production performance by optimizing the system′s scale and buffer capacity. The numerical experiments were conducted to verify the effectiveness of this model.