Abstract This paper introduces a smart grid environment authorization service architecture based on XACML and SAML standards. Software prototypes are deployed with the platform as a service (PaaS) framework Appscale. Appscale is an open source AppEngine framework released by Google that can execute applications in the cloud to solve the problems caused by the distributed computing model. This paper mainly evaluates its scalability. Through the different configuration of all distributed databases, the test of the system running load is completed. The test results show that the number of nodes deployed by Appscale varies from very unstable behavior to waiting scalability.