This paper presents the experimental results of impulse breakdown characteristics in $SF_6/N_2$ gas mixtures under a highly non-uniform electric field with a change in temperature. The test temperature ranges from -25[$^{circ}C$] to 25[$^{circ}C$]. The processes of impulse preliminary breakdown developments were analyzed by the measurements of current pulse and luminous signals. As a result, the temperature dependance of breakdown voltage for the negative polarity was much stronger than that for the positive polarity. When increasing the temperature, The leader stepping time for the negative polarity was shown to be longer than that for the positive polarity. The results presented in this paper can be used as a useful information in designing the gas insulation lines with prominent ability for lightning surge.