This paper analyzes the large area blackout accident in the Qilu company on November 18th and offers the prevention measures in order to lessen such these accidents.

In this paper the process of blackout occurred in 220kV Caoqiao substation of Beijing power network in China on March 21, 2008 is presented.

Recent studies on the power systems collapse prevention and the mechanism of cascading failures have shown that the self-organized criticality (SOC) is the character of power system blackouts.

Based on the concept of self-organized criticality (SOC) and fractal and by analyzing power system blackouts in China from 1981 to 2002, the characters of SOC of domestic power system blackouts are revealed, and the scale-frequency models for blackouts occurred in nationwide power grid as well as in Northeast China, Central China and Northwest China power grids are constructed.

Based on the concept of fractal, the relationship models between the power loss and frequency of electric power system blackouts are constructed.

The application of the complex network theory to the power grid is introduced,and the method and importance of using the theory to analyze blackouts are illuminated,as well as how to analyze the dynamic charac- teristics of power grids based on the theory.

But recently,successive power blackouts of large scale occurred in the world,result in a great loss,which attracts researchers attention to the reliability of power grid.