When deploying and implementing a cloud platform, it is necessary for vendors to manage and control their software of the cloud platform. To solve the problem that currently there is few authorization model in cloud platform software management and control, we propose and design a mechanism for cloud platform software authorization based on RSA algorithm within the progress of building the cloud management system of a real project. The practice has proved that the authorization mechanism in this paper, by monitoring and manipulating the validity of underlayer resource in the platform, is effective to manage and control the cloud platform software usage, which can be generalized for cloud platform software authorization in many other cases.