Abstract: For the existing temperature carrying capacity calculation models of transmission lines depending on the environment meteorological data, a kind of carrying capacity calculation method, live analogy, is proposed. A conductor whose temperature can be controlled is set near the transmission conductor, and it is heated until the temperature reaches the maximum allowable temperature. The maximum carrying capacity can be calculated by measuring the temperature of the heated conductor and the heating power. In order to reduce the operation temperature of the heated conductor, a low temperature operation mode of live analogy model is put forward, by using of which the maximum carrying capacity can be calculated by measuring the temperature of reference conductor and heated conductor and its heating power through setting a reference conductor near the transmission lines again. In the end, the feasibility of carrying capacity calculation by using of the live analogy method is verified through experiments and a dynamic compatibilization device of transmission line is designed based on proposed principle.