Based　on　an　information　acquisition　system,　the　dynamic　characteristics　of　the　pressure　signal　for　resistance　spot　welding　of　aluminum　alloy.　The　pressure　signals　of　splashing　spot　and　normal　spot　are　compared　and　analyzed　in　time　and　frequency　domains.　It　was　found　that　there　is　a　sudden　change　in　the　pressure　signal　of　splashing　spot　with　obvious　characteristic　frequency,　while　the　normal　spot　has　no　such　phenomenon;The　db5　wavelet　is　used　to　decompose　the　pressure　signal　into　seven　levels　to　obtain　the　waveforms　in　time　and　frequency　domains　and　the　energy　ratio　of　detail　signals　in　different　frequency　bands.　The　results　showed　that　according　to　different　forms　and　characteristics　of　the　pressure　signal,　the　standard　deviation　of　the　pressure　signal　during　the　power　phase,　the　peak-peak　value　in　the　target　level,　the　highest　value　of　the　energy　ratio　and　the　number　of　level　in　the　target　layer　of　the　wavelet　decomposition　detail　signal　can　be　extracted　as　the　characteristic　index　to　identify　splashing　spot.　©　2020,　Editorial　Board　of　Transactions　of　the　China　Welding　Institution,　Magazine　Agency　Welding.　All　right　reserved.