Cloud computing systems promise to offer pay per use, on demand computing services to users worldwide. Recently, there has been a dramatic increase in the demand for delivering services to a large number of users, so they need to offer differentiated services to users and meet their expected quality requirements. Most of scheduling schemes proceeding nowadays have no QoS (Quality of Service) differentiation, which is necessary for Cloud Computing service operation. As a cloud must provide services to many users at the same time and different users have different QoS requirements, the scheduling schemes should be developed having different QoS requirements. So, this paper explores various methods of task scheduling done in cloud computing. Real-time applications play a significant role in cloud environment. We have examine the particular scheduling algorithms for real-time tasks, that is, priority-based strategies.The purpose of this paper is to discuss the fixed priority preemptive task scheduling algorithms in cloud computing for improving the QoS parameters.