This paper has been addressed on the discharge characteristics of the ignition coil by Weibull function. It analyzed discharge number and amount of discharge using Weibull distribution to know the inter-relationship between partial discharge and mileage. We detected the discharge which happens for 10 seconds. The applied voltage increased by 0.5[kV] at discharge inception voltage. We diagnosed failure rate using the shape parameters. As a result, we confirmed that the failure rate was increased, because the shape parameter showed the value of 5 according to increasing mileage degradation. Also, it is considered to increase the degradation of inner insulator of ignition coil. Because failure rate of virgin was increased from 0[%] to 25[%] after degradation, stability analysis of the ignition coil using Weibull analysis is possible.