The　vibration　fatigue　life　and　vibration　response　signal　at　the　dangerous　position　of　each　specimen　were　obtained　by　the　broadband　random　vibration　fatigue　test　for　7075-T651　aluminum　alloy,　and　the　stress　amplitude　probability　distribution　of　vibration　response　signal　was　counted　by　rainflow　counting　method.　By　comparing　the　probability　density　distribution　functions　of　broadband　random　vibration　signal　by　frequency-domain　method　and　analyzing　the　fitting　accuracy　of　different　distribution　models　for　rainflow　distribution,　a　new　model　for　frequency-domain　fatigue　life　prediction　based　on　modified　narrowband　distribution　model　was　proposed.　The　proposed　model　takes　the　second-order　spectral　width　parameter　of　vibration　signal　as　the　weight　coefficient,　and　the　life　prediction　results　are　more　accurate　and　less　dispersive.