Surface　pretreatment　is　of　great　significance　for　improving　the　welding　quality　of　metal　materials,　especially　aluminum　alloys.　At　present,　the　welding　process　is　introduced　to　join　the　laser　powder　bed　fusion　(LPBF)　AlSi10Mg　alloys　or　their　repair　during　manufacturing　or　service.　However,　the　high　susceptibility　of　hydrogen　pores　is　one　of　the　most　important　problems　encountered　in　the　fusion　welding　process　of　LPBF　AlSi10Mg　alloys.　To　clarify　the　influence　of　the　surface　state　of　the　base　metal　on　the　hydrogen　pore　characteristics,　the　LPBF　AlSi10Mg　sheets　were　pretreated　by　chemical　cleaning　treatment　(CCT),　mechanical　polishing　treatment　(MPT),　and　chemical　cleaning　treatment　after　mechanical　polishing　treatment　(MPT-CCT)　before　laser　welding.　Subsequently,　the　hydrogen　pore　characteristics,　microstructure,　and　micro-hardness　of　the　welded　joints　were　investigated.　The　experimental　results　show　that　laser　welding　with　MPT-CCT　significantly　reduces　the　porosity　and　pore　diameter.　In　addition,　MPT-CCT　can　eliminate　most　of　the　broken　and　discontinuous　surface　oxide　film　and　Mg　enrichment.　In　summary,　the　necessity　of　MPT-CCT　for　LPBF　AlSi10Mg　alloys　is　analyzed　systematically,　which　is　of　great　significance　to　improve　the　welding　quality.