Taking the differences in the operation needs of different components of the power system into account, a method for calculating the thermal stability control limit of components considering the structural vulnerability of the components and the uncertainty of the environmental temperature is proposed. By integrating the transfer coefficient multiplexing index and transferring the Theil entropy index as component weight indicators, a thermal stability limit calculation model that improves the safety margin of vulnerable components is established. Furthermore, the uncertainty of the component's environmental temperature is considered by using the opportunity constraints of the dynamic current carrying capacity of the wire to replace the traditional short-term overload capacity constraints. The transmission potential of existing equipment is tapped and the risk caused by the environmental temperature exceeding the agreed value of the regulations is reduced. The analysis of a numerical example validates the effectiveness of the proposed method. This work is supported by Youth Science Fund of National Natural Foundation of China (No. 51807114) and Technology Program of Shanghai Municipal Science Committee (No. 18DZ1203200), and Shanghai Engineering Research Center of Green Energy Grid-connected Technology (No. 13DZ2251900).