The invention relates to the field of cloud computing, in particular to a cloud-computing-based platform as a service (PaaS) platform system and an implementation method thereof. The system comprises a service request management module, a software as a service (SaaS) application system, a service publication system, a cloud operating system, a marketing management system, cloud computing service and a cloud computing hardware virtualization framework. The implementation method comprises the following steps of: performing hardware virtualization on a server cluster by utilizing the cloud operating system, configuring different operating systems according to different requirements of the application system, and dynamically and uniformly allocating and managing hardware resources; and binding users of different systems with different user authentication certificates, adopting the active encryption of real-time encryption and decryption to prevent breach of confidence, and controlling the rights of the application system integrated on a PaaS platform. The problems about the independence, security and high-efficiency resource utilization of the system are solved; and the method can be applied to the cloud-computing-based PaaS platform system.