To fully utilize the latent transmission capacity of power lines without increasing the maximum allowable operating temperature of the conductors, the current-carrying capacity of the conductors is dynamically adjusted in real-time based on monitored data of actual environmental factors. Firstly, a multi-physical field coupling 3D model of a steel-cored aluminum stranded conductor is established, considering the lay ratio and lay direction of each conductor layer. The model is used to analyze the effects of environmental wind speed, solar radiation intensity, ambient temperature, and current load on the temperature rise of the line. Simulation results indicate that the maximum conductor temperature under high wind speed conditions is 23.8 ℃ lower than under low wind speed conditions, demonstrating a significant temperature difference. A conductor temperature rise platform was constructed to conduct temperature rise tests under different environmental parameters. The error between the forced convection simulation results and the experimental data was 6.58%, partially validating the accuracy of the simulation model. Different environmental parameters and temperatures affect the maximum current-carrying capacity of the conductor. In a laboratory environment, with a wind speed of 3.5 m/s, the conductor carrying the maximum allowable temperature had a current-carrying capacity 15.2% higher than the calculated value by formula, and 92.1% higher than the design value. The results of this study can provide a theoretical basis for the dynamic adjustment of transmission capacity in power transmission lines.