Deep　rock　structures　are　often　subjected　to　complex　cyclic　disturbances　generated　by　earthquakes　and　blasting　vibrations.　The　rocks　will　resist　disturbance　with　multiple　stress　levels,　and　the　research　on　mechanical　response　is　still　insufficient　under　such　conditions.　A　series　of　multi-level　cyclic　loading　experiments　were　subjected　to　limestone　specimens　to　obtain　the　stress-strain　relation　and　fracture　behavior.　This　study　explored　the　effect　of　amplitude　and　cycle　times　on　rocks.　A　Discrete　Element　Method　model　of　rock　specimens　was　established　in　Particle　Flow　Code　2D　(PFC2D).　The　simulation　results　are　coincidental　with　the　experiment　results.　The　results　show　that　loading　with　low　cycles　can　strengthen　the　rock,　but　loading　with　high　cycles　will　present　deteriorated　effect　on　the　rock.　In　the　numerical　simulation　test,　the　initial　crack　will　appear　earlier　with　the　amplitude　increase.　More　micro　cracks　will　be　induced　as　the　number　of　cycles　per　level　increases.　Moreover,　tensile　cracks　are　mainly　distributed　around　the　specimen　when　shear　cracks　widely　appear　in　the　central　area.　With　the　increase　of　amplitude,　failure　modes　with　mixed　shear　and　tensile　cracks　will　become　universal.