Multistage compression systems (MSCS) are the most important and valuable facilities in chemical plants, whose failure may cause severe accidents and/or tremendous economic loss. Thus, operation for MSCS needs sufficient care under various Situations, especially during plant startup. This paper employs rigorous pressure-driven dynamic simulations to examine and improve operation safety of the cracked gas compression system during in ethylene plant startup, For safety consideration, antisurge process design and control strategies are dynamically evaluated along with startup procedures. Operating point trajectory for each compressor and their potential safety problems are identified. Assisted by the rigorous dynamic simulation, the plant startup procedure is improved with better safety performance.