Aiming at embedded realtime system task scheduling problems, the scheduling strategy of integrating two characteristic parameters (deadlines and criticalness), was studied. A dynamic deadlinecriticalness algorithm was presented. The algorithm does the following: groups tasks; partitions priorities; changes the scheduling strategy dynamically based on the judgment function; employs a strategy of reaching the earliest deadline first (EDF) to lower the task missed deadline percentage; and uses the criticalness to guarantee the task scheduling success ratio. Theoretical analysis and experimental simulation show that this algorithm achieves the same performance as EDF under nonoverload conditions. The algorithm can improve the scheduling success ratio of critical tasks compared with the classical EDF and fixed priority algorithms under overload conditions.