On June 5, 2017, there was a Vapor Cloud Explosion (VCE) at JinYu Petrochemical Co. Ltd. During unloading of liquified natural gas, the gas leaked from the truck and formed a vapor cloud, then the vapor cloud met with the electrical sparks in the plant laboratory, and an explosion occurred. This incident caused significant casualties and property loss. The main causes of the accident are demonstrated by a fishbone diagram. The major causes include (a) defective design, (b) noncompliance with standard operation procedures (SOPs), (c) the presence of ignition sources, (d) ineffective enforcement of safety rules, (e) inadequate design of emergency facilities, and (f) delayed emergency response. The analysis reveals that process safety management (PSM) is a crucial factor in the success of chemical plants, especially for small and median-scale companies in developing countries. Dispersion phenomenon of liquefied gas is simulated by commercial Computational Fluid Dynamic (CFD) software. The simulation results approximately agree with the real incident. The simulation indicates that a visual and quantitative consequence analysis can provide general guidance for PSM. Finally, based on various PSM conditions (good, normal, weak, and bad), the probabilities of VCE generated from leakage are obtained by an event sequence diagram (ESD) and Monte Carlo methodology. By comparing the quantitative probability values in four different PSM situations, the results show that emergency management associated with effective PSM is crucial to avoid VCE incidents.