Abstract: Mixed-criticality system is one of the main trends in the development of modern embedded systems. The high critical task represents the practical task with high urgency or importance, which usually needs to be guaranteed first. In order to ensure the execution of high-level critical tasks, the current mixed critical task scheduling algorithms often discard or schedule low-level critical tasks in a timely manner. As a result, the task loss time limit rate is large and the system utilization rate is low during the critical level conversion. Therefore, the EDF-os semi-partition scheduling algorithm is improved in hybrid critical systems with dual critical levels. First, in the division phase, the tasks at high critical levels are treated as fixed tasks and the tasks at low critical levels are divided by utilization using the Worst-Fit policy. Secondly, in the execution phase, the form of job boundary migration is used, and the strategies for determining the priority of tasks at different critical levels under different system critical levels are discussed in detail, and tasks are scheduled according to the priorities. Finally, a multi-processor hybrid critical system with dual critical levels is simulated, and task sets are randomly generated for simulation experiments. The results show that the proposed method increases the executable ratio of low-critical level tasks by 14.8% on average, and decreases the task loss time rate by 19.7%.