A　kind　of　audio　bandwidth　extension　method　based　on　Grey　Model　is　proposed　in　this　paper.　Grey　Model　is　utilized　for　estimating　the　envelope　of　high-frequency　spectrum,　according　to　the　evolutionary　tendency　of　audio　spectral　envelope.　In　addition,　nearest-neighbor　matching　is　utilized　to　predict　the　fine　spectrum　of　high-frequency　components.　At　last,　through　the　envelope　adjustment　of　high-frequency　spectrum,　the　bandwidth　extension　of　audio　signals　from　wideband　to　super-wideband　can　be　implemented.　Objective　performance　evaluation　indicates　that　the　proposed　method　can　effectively　reconstruct　the　truncated　high-frequency　components　and　outperform　the　conventional　method　of　audio　bandwidth　extension　based　on　Gaussian　mixture　model.