Spatters　in　laser　penetration　welding　of　aluminum　alloys　affects　the　process　stability　and　reflects　the　laser　welding　process　to　a　certain　degree.　The　spatter　characteristics　in　CO2　laser　and　fiber　welding　of　6061-T6　aluminum　alloy　were　investigated,　and　the　reasons　for　the　difference　in　spatter　characteristics　were　discussed.　Dynamic　behavior　of　spatters　was　recorded　in　real-time　by　a　high-speed　camera.　The　spatter　particles　were　captured　and　their　sizes　were　measured　experimentally.　Probability　density　functions　(PDFs)　about　the　spatter　velocity　and　size　were　fitted　by　Ordinary　Least　Squares　(OLS)　method　in　X2　test.　The　result　indicates　that　the　spatter　speed　follows　Gaussian　distribution　and　the　particle　size　follows　lognormal　distribution　in　both　cases.　However,　the　statistical　speed　of　spatters　is　faster　in　fiber　laser　welding,　which　indicates　that　more　attention　should　be　paid　to　protect　the　focusing　system.　Moreover,　the　statistical　diameters　of　the　spatter　particles　are　smaller　and　PDFs　of　the　particle　size　is　more　fit　with　Lognormal　distribution　in　fiber　laser　welding,　which　means　that　fiber　laser　welding　process　is　more　stable　than　CO2　laser　welding　process.