Digital twin (DT) provides a solution for supporting the interconnection between the physical world and the virtual world. When implementing DT integration, it is challenging to implement interface definition, information and service integration across DTs. This paper proposes a semantic modeling approach with a High-Level Architecture (HLA) to support the DT integration. The semantic modeling approach based on Graph-Object-Property-Point-Role-Relationship (GOPPRR) meta-meta models is used to realize the integrated formalisms of heterogeneous DTs. HLA is used to support interface definition and service integration between virtual entities of DT. Finally, a case of an unmanned aerial vehicle (UAV) landing on ship is used to verify the flexibility of this approach. From the results, we find the GOPPRR ontology and HLA specification enables to provide a unified formalism of the DTs of UAV and the ship, and to implement data exchange during the distributed simulation execution.