The electrical breakdown characteristics of liquid nitrogen(LN$sub$2/) were studied under simulated quenching conditions for application of HTS apparatus. The experimental results for various quenching condition revealed that the breakdown voltage of LN$sub$2/ with bubble flow velocity and gap spacing. In the case, breakdown voltage decreases gradually with the bubble velocity. When it is bubble velocity from 0 to 1 $ell$ /min, breakdown voltage rapidly decreases but decreases from 2 $ell$/min to 10 $ell$/min slowly. The breakdown voltage for vertical electrode arrangement is higher than that for horizontal electrode arrangement. Also, it did a electric field and potential distribution interpreting at the liquid nitrogen when the bubble existed. The plots of equipotential lines for three cases are also shown.