This paper study the power fault online avoidance strategy to improve the reliability of power source. According to real-time monitoring of the power running status, confirm the property and urgency degree. Through adaptive adjusting the stress on the component and executing the sound software shut off method, targeted protect the power source into different levels. The results show the occurrence probability of power source faults decrease and time between failures increase. This is especially applicable to severe environments and fields where power source should have high reliability.