Since the severity and frequency of extreme events have seriously threatened the stability of fossil energy markets, this paper conducts multilayer dynamic network analysis to demonstrate the evolution of the entire market structure during extreme events. Based on the data of 64 Chinese energy firms ranging from March 2018 to February 2023, this paper examines the sectoral discrepancies, and identifies systemically important companies during different crises. The results indicate that the risk transmission mechanisms among fossil energy markets are different induced by the two crises, namely the COVID-19 pandemic and the Russia–Ukraine conflict. Specifically, the COVID-19 has rendered greater influence on the oil and gas industry, while the Russia–Ukraine conflict has brought instability to the coal industry. Additionally, the heterogeneous effects of these events on individual energy firms are identified, and the results suggest that both small and large firms have played prominent roles in risk transmission.