Generation　outages,　transmission　line　contingencies,　natural　gas　pipeline　contingencies,　compressor　failures　as　well　as　gas　source　and　load　fluctuation　are　posing　a　great　threat　to　the　secure　operation　of　a　combined　natural　gas　system　and　power　system(CGPS).　To　quantify　the　risk　level　caused　by　these　dangerous　factors,　this　paper　proposes　a　generalized　CGPS　risk　assessment　model,　in　which　the　modeling　of　linepack　of　pipeline　and　gas　tank　are　taking　into　account.　Besides,　by　calculating　the　specific　electricity　and　gas　load　loss　utilizing　a　state-based　non-sequential　Monte　Carlo　method,　the　effects　of　linepack　and　gas　storage　tank　on　improving　the　whole　reliability　level　of　the　CGPS　can　be　quantitatively　assessed.　Finally,　the　evaluation　model　is　validated　by　a　combined　6-node　electricity　network　and　14-node　gas　network　test　case.　The　results　show　that　the　proposed　model　can　effectively　assess　the　influence　of　those　uncertainties　on　the　combined　system　risk　level,　and　the　contribution　of　linepack　and　gas　storage　tank　on　the　resilience　of　the　integrated　system　can　also　be　quantitative　calculated　by　given　indicators.　©　2019　IEEE.