Abstract: In order to reduce the use of SF₆ in power equipment, we investigated the application feasibility of eco-friendly SF₆-alternative gas HFO-1336mzz(E) as the arc extinguishing medium in a 12 kV load switch. We established a two-dimensional magnetohydrodynamic simulation model and calculated the current interruption process in the puffer-type load switch. Moreover, we studied and compared the arc voltage, temperature field, airflow field distribution in the arc extinguishing chamber during the arcing period and the thermal interruption capability during the post-arc period for the 30%HFO-1336mzz(E)/CO₂ (0.12 MPa), 30%HFO-1336mzz(E)/air (0.1 MPa) and SF₆ (0.1 MPa). The studies show that the arc quenching peak of HFO-1336mzz(E) gas mixtures is slightly greater than that of SF₆, and the arc diffusion in the axial direction is greater than that of SF₆. When the current nearly exceeds zero, the arc temperature of HFO-1336mzz(E) gas mixtures is 1400 K lower than that of SF₆. By analysis, the thermal interruption capability of 30%HFO-1336mzz(E)/CO₂ and 30%HFO-1336mzz(E)/air gas mixture can reach 95% and 96% that of SF₆, respectively. The results can provide reference for HFO-1336mzz(E) gas mixtures as arc extinguishing medium in medium voltage switchgears.