To　identify　the　aeroelastic　effects　on　bridge　decks　during　vortex-induced　vibration　(VIV),　a　new　method　is　proposed.　The　procedure　of　instantaneous　identification　of　the　VIV　system　is　firstly　proposed.　Based　on　this　procedure,　the　method　for　extracting　the　aeroelastic　damping　and　stiffness　from　the　total　damping　and　stiffness　of　the　VIV　system　is　establised.　Data　of　wind　tunnel　experiments　on　an　open-section　bridge　deck　undergoing　vortex-induced　resonance　is　involved　for　validation　and　for　studying　the　features　of　aeroelastic　effects　on　this　deck　during　VIV.　The　zero-contour　of　the　total　damping　for　the　VIV　system　compares　well　with　the　experimental　VIV　responses,　which　confirms　the　accuracy　of　this　method.　Based　on　the　results,　aeroelastic　effects　at　different　wind　velocities　and　amplitudes　on　this　open-section　bridge　deck　are　studied　in　detail,　which　can　offer　some　valuable　information　for　the　subsequent　study　on　mathematical　modeling　of　this　phenomenon.　©　2017,　Editorial　Board　of　Journal　of　Harbin　Institute　of　Technology.　All　right　reserved.