FMI 1.0 is exported through EnergyPlus, and is not displayed after Imported in OpenMolica. The size of .mo file is 0k.

Export FMI2.0, which is the type of CoSimulation, and report an error:
The FMU version is 2.0 and FMU type is CoSimulation. Unsupported FMU type. Only FMI 2.0 ModelExchange is supported.

How to import FMU file of EnergyPlus into OpenModelica and calculate.

The implementation supports FMI for Model Exchange 1.0 & 2.0 and FMI for Co-Simulation 1.0 stand-alone. The support for FMI Co-Simulation is still under development.
The FMI Import is currently a prototype. The prototype has been tested in OpenModelica with several examples. It has also been tested with example FMUs from FMUSDK and Dymola. A more complete version for FMI Import will be released in the near future.

Thanks!