Power system is a complex system， and has important self-organized criticality characteristics. Firstly， a sand pile model is built， and through the simulation on this model， the power law relationship between cascading scale and the corresponding frequency is verified. Secondly， the control measures are added to this model， the influence of the control rules on the system under long-term span is established. Three control rules are added into sand pile models， such as small-stick mechanism， decrease of fault transfer and active splitting control， and new power law functions are obtained respectively to satisfy the self-organized criticality. Compared with the power law function from sand pile model without imposed rules， slopes of the new power-law functions increased in log-log coordinates， which means that the probability of large-scale accidents is reduced under the three rules. Therefore， appropriate control rule is an important factor to prevent large power outage， and these three rules are proposed as effective ways to prevent and alleviate blackout of power systems.