As　an　analog　of　the　optical　frequency　comb,　the　phononic　frequency　comb　has　been　demonstrated　in　mechanical　resonators　recently.　In　this　Letter,　we　generate　the　frequency　comb　in　a　rhombic　micro-resonator　with　stiffness　parametrically　modulated　by　low-frequency　pumping.　Interestingly,　this　comb　exhibits　the　asymmetry　in　the　amplitude,　i.e.,　the　amplitudes　of　comb　fingers　on　either　side　of　the　central　comb　finger　decay　with　different　rates.　With　a　parametrically　modulated　model,　we　analyzed　in　detail　the　asymmetry　in　the　frequency　comb　and　accurately　captured　the　reason　for　the　asymmetry.　Furthermore,　the　asymmetry　of　the　frequency　comb　can　be　adjusted　experimentally.　These　results　provide　a　theoretical　basis　for　manipulating　the　comb　fingers　and　are　expected　to　open　the　door　for　potential　applications　of　the　frequency　comb.　©　2021　Author(s).