In　this　study,　a　weakly　conditionally　stable-body　of　revolution-finite-difference　time-domain　(BOR-FDTD)　method　is　presented　to　simulate　a　dielectric　film-coated　circular　waveguide.　The　time-step　size　for　this　method　only　depends　on　the　spatial　cell　size　Delta　z.　The　formulas　of　the　method　are　presented　and　its　time　stable　condition　is　demonstrated.　Numerical　results　show　that　when　this　method　is　applied　to　simulate　the　dielectric　film-coated　circular　waveguide,　it　is　more　efficient　than　the　conventional　BOR-FDTD　method　in　terms　of　computation　time.