We　present　a　method　of　estimating　quality　factor　Q　from　CMP　records,and　a　method　of　estimating　layer　positions　based　on　coherent　characteristics　of　traces.　First,　employing　a　function　with　four　undetermined　parameters　to　approximate　the　source　wavelet,　the　relation　between　the　instantaneous　frequency　(IF)　at　the　envelope　peaks　of　seismic　wavelets　(EPIF)　and　traveltime　at　different　offsets　is　derived　based　on　the　theory　of　one-way　wave　propagation　in　a　ID　viscoelastic　medium;　then　by　using　the　relationship,　we　extrapolate　the　EPIF　of　zero　offset　of　the　event;　finally,　Q　is　estimated　by　combining　WEPIF　with　the　reflectivities　information.　Applied　to　synthetic　pre-stack　CMP　models　and　the　result　indicates　that　the　method　has　no　boundary　effect　and　is　more　precise;　we　also　apply　the　method　to　field　record,　it　produces　a　Q-curve　indicating　that　the　extent　of　absorption　corresponds　well　to　the　gas　saturation　of　reservoirs.