As the core component of the spacecraft power supply system, the safety and stability of Printed Circuit Boards (PCB) are very important for the whole spacecraft operation. However, PCB faces more insulation problems under abnormal operating conditions. On the one hand, miniaturization and high-density electrical devices result in continually decreasing insulation distance between PCB interconnection system, and the decreasing of insulation distance decreased the ability of resisting over voltage. On the other hand, PCB mainly affected by temperature, high vacuum under the abnormal operating conditions which accelerated aging of PCB. In this paper, the interconnection structure of PCB is designed and the effects of interconnection spacing, temperature, pressure and pulse width on the breakdown voltage of PCB are studied. The results indicated that the breakdown characteristics of PCB obey the Weibull distribution and the breakdown voltage of PCB with increasing interconnection spacing generally showed a linear increasing trend and with the increase of the pulse width, the breakdown voltage is decreased. With the increase of the temperature, the breakdown voltage is decreased. And the result also shows that the low pressure will weaken the insulation ability of the PCB.