To solve the information fusion and situation awareness issues of terminal decision-making groups in emergency rescue of major chemical fires，a fire situation awareness model for large-scale storage tanks was proposed based on the evolution characteristics of the storage tank fire situation and the multi-layer network theory. A network edge weight calculation method based on Bayesian parameter estimation was proposed by developing a chemical storage tank fire situation information set. Node importance and inter-layer correlation coefficient were used to present the connection strength of nodes within the network layer and the correlation strength between network layers，respectively. Moreover，the evolution trend of key situations within and between storage tanks was identified. Then，the evolution process of the fire emergency rescue situation in a tank was analyzed. The results indicated that the situation awareness model based on multi-layer networks can better analyze the fire situation evolution characteristics of large storage tanks. The greater the importance of the node，the faster the fire evolution of the corresponding storage tank. The stronger the correlation between layers，the more significant the evolution trend between adjacent storage tanks.