The invention relates to a method for preventing industrial automation system from avalanche, in which the industrial automation system comprising a storage unit for storing time stream data to be processed and a CPU for processing the time stream data in the storage unit, the method comprises the following items: 1) establishing a data processing task priority level; 2) scheduling the data processing task of the CPU; 3) using method of the storage unit. Under a given CPU processing ability, the time stream data to be processed is set with different priority levels, the CPU firstly processes the to-be-processed data processing task with the highest priority level and then processes those with the next priority level. And the storage unit is also set with the corresponding sub-storage units with different priority levels in accordance with the priority levels of the to-be-processed data processing task. The to-be-processed data processing task with higher priority level can be stored or cover those with lower priority level. Therefore, it can effectively ensure that the automation system deals with unexpected number of tasks without causing the crash of the system under a given CPU processing ability.