Dear @jyoti.grg
unfortunately there is no direct support of CAD in fluka. However there are some ways you can use a CAD geometry
- FluDAG: CAD files in FLUKA: FLUDAG
- MCACM: https://sna-and-mc-2013-proceedings.edpsciences.org/articles/snamc/abs/2014/01/snamc2013_02508/snamc2013_02508.html
- Ansys Workbench (export to MCNP and import in flair the MCNP)