In this paper, an efficient algorithm is presented to dynamically schedule the task sets combining hard and soft real-time tasks in heterogeneous systems. The proposed algorithm improves the scheduling success ratio by introducing a new task assignment policy and a QoS (quality of service) degradation policy for soft real-time tasks. To evaluate the performance of the new algorithm, extensive simulation studies have been done. These simulations apply myopic algorithm to schedule the hard and soft real-time tasks in heterogeneous systems and use it as a baseline to compare with the proposed algorithm. Simulation results show that the scheduling success ratio of the new algorithm is always higher than that of myopic algorithm in real-time heterogeneous systems for a variety of task parameters.