The　reassignment　method　is　a　widespread　approach　in　processing　nonstationary　signals　for　obtaining　high　aggregation　and　less　overlapping　components　in　time-frequency　representations.　Unfortunately,　by　using　this　traditional　method,　there　exist　some　problems　such　as　unavoidable　overlapping　components　and　low　signal-to-noise　ratio　values.　A　novel　time-frequency　reassignment　method　based　on　nonparametric　snakes　is　proposed　for　guided　wave　mode　identification　of　steel　strands.　According　to　research　results,　it　is　clarified　the　proposed　reassignment　method　based　on　nonparametric　snakes　can　obtain　high　resolution　time-frequency　representations　with　significantly　higher　aggregation　and　improved　signal-to-noise　ratio　compared　with　the　short-time　Fourier　transform　and　traditional　reassignment　method.　Furthermore,　compared　with　group　velocity　dispersion　curves　in　one　of　helical　wires　of　the　steel　strand,　the　spectrogram　provided　by　the　proposed　method　can　give　the　information　of　main　ultrasonic　guided　wave　modes　and　describe　the　trend　of　group　velocity　changes　of　these　modes　more　accurately.　Therefore,　the　proposed　time-frequency　reassignment　method　can　provide　a　valuable　basis　for　improving　ultrasonic　guided　wave　identification　in　different　waveguides.　©　2011　Journal　of　Mechanical　Engineering.