Simulation can benefit from cloud computing that often comes with thousands of processors and its soft-ware is structured as Software-as-a-Service (SaaS) with its Multi-Tenancy Architecture (MTA). To sup-port multiple tenants, simulation SaaS models need be modeled and customized to fulfill the various functional and quality requirements of individual tenants. The multitude options of tenant-specific data have made the simulation models and execution processes rather complicated. This paper presents P4-SimSaaS that comes with an new ontology system and an innovative tenant related policy specification for Simulation SaaS. P4-SimSaaS can reduce the complexity in the MTA simulation models and consequently increase the flexibility in MTA simulation execution environment. A case study is offered to demonstrate the entire framework.