It　is　difficult　to　realize　the　quantitative　detection　of　defects　by　using　the　time　domain　or　frequency　domain　features　of　Lamb　wave　signals　due　to　their　dispersion　and　multi-mode　characteristics.　This　paper　proposes　a　method　for　analyzing　the　propagation　characteristics　of　laser-induced　Lamb　waves　in　frequency-wavenumber　domain.　Based　on　a　full-optical　laser　ultrasonic　testing　system,　time-space　wavefield　signals　were　obtained　by　the　pulse　laser　excitation　in　a　fixed　location　and　continuous　laser　acquisition　with　one-dimensional　scanning,　where　the　propagation　characteristics　of　laser-induced　Lamb　wave　signals　and　the　regular　pattern　of　the　interaction　between　the　laser-induced　Lamb　wave　signal　and　the　defect　can　be　visually　displayed.　The　two-dimensional　Fourier　transform　was　used　to　convert　the　wavefield　signals　from　the　time-space　domain　to　the　frequency-wavenumber　domain　where　individual　modes　including　in　the　signals　are　well　discernible.　Based　on　the　idea　of　short-time　Fourier　transform,　for　retaining　the　space　information,　a　short-space　two-dimensional　Fourier　transform　was　adopted　to　obtain　the　distribution　of　wavenumber　along　the　scanning　path,　by　which　the　location　of　the　defect　can　be　visually　displayed.　The　results　of　short-space　two-dimensional　Fourier　transform　were　optimized　by　using　band-pass　filtering　combined　with　continuous　wavelet　transform.　The　experiments　performed　on　pristine　and　defected　aluminum　plates　respectively　confirm　the　effectiveness　of　the　method.　©　2019,　Editorial　Office　of　Journal　of　Vibration　and　Shock.　All　right　reserved.