Frequency　comb　in　microelectromechanical　systems　has　attracted　many　concerns,　which　is　expected　to　realize　great　achievements　analogous　with　the　optical　frequency　comb.　Previous　frequency　combs　are　generated　by　mode　coupling　in　a　single　micro-resonator.　To　pursuit　more　excellent　tunability　and　robustness,　it　is　impending　to　create　a　frequency　comb　through　another　way,　i.e.,　coupled　but　relatively　independent　micro-resonators.　In　this　work,　a　frequency　comb　in　1:3　internal　resonance　region　of　an　electrostatically　coupled　microsystem　is　reported.　We　demonstrate　the　occurrence　conditions　and　its　influencing　factors　of　the　frequency　comb.　A　dynamical　explanation,　which　has　good　agreement　with　the　experimental　results,　is　presented　to　further　reveal　its　intrinsic　mechanism.　Our　finding　provides　a　controllable　method　to　produce　a　frequency　comb　that　is　beneficial　to　potential　applications,　such　as　signal　processing　and　sensing　sensitivity　enhancement.　©　2022　Author(s).