The increasing popularity of quantum computing has resulted in a considerable rise in demand for cloud quantum computing usage in recent years. Nevertheless, the rapid surge in demand for cloud-based quantum computing resources has led to a scarcity. In order to meet the needs of an increasing number of researchers, it is imperative to facilitate efficient and flexible access to computing resources in a cloud environment. In this paper, we propose a novel quantum computing paradigm, Virtual QPU (VQPU), which addresses this issue and enhances quantum cloud throughput with guaranteed circuit fidelity. The proposal introduces three innovative concepts: (1) The integration of virtualization technology into the field of quantum computing to enhance quantum cloud throughput. (2) The introduction of an asynchronous execution of circuits methodology to improve quantum computing flexibility. (3) The development of a virtual QPU allocation scheme for quantum tasks in a cloud environment to improve circuit fidelity. The concepts have been validated through the utilization of a self-built simulated quantum cloud platform.