Resistance　spot　welding　quality　real-time　monitoring　of　aluminum　alloy　was　realized　by　distributed　multiple-sensor　synchronous　collection　system.　Displacement　signal　time-frequency　domain　analysis　shows　that　Butterworth　band-pass　filter　range　of　the　expulsion　welding　spot　electrode　displacement　signal　can　reach　about　0.5　mm　between　40-80　Hz.　The　electrode　displacement　signal　range　of　the　undersize　welding　spots　is　lower　about　1.0　mm　than　other　two　kinds　of　welding　spots,　so　that　using　the　explicit　characteristic　information　can　implement　at　resistance　spot　welding　quality　judgment　by　man　and　further　can　finish　quality　judgment　by　machine　using　the　high　signal-to-noise　displacement　signal　and　the　brevity　characteristic　extracting　method.　At　the　same　time,　statistic　analysis　of　197　samples　indicates　that　the　percentage　of　accuracy　can　reach　97.6%　at　the　acceptable　welding　spots　zone.