As　a　method　of　work　hardening,　the　technology　of　in-situ　forging　was　introduced　to　solve　the　problem　of　poor　mechanical　properties　in　the　fabrication　of　large-structural　aluminum　alloys　components　using　wire　arc　additive　manufacturing　(WAAM)　technology.　Unfortunately,　at　present,　the　in-situ　forging　devices　reported　could　not　provide　the　ability　to　flexibly　adjust　output　forces　over　a　wide　range　of　frequencies　and　change　the　output　mode　of　forces.　In　this　work,　a　novel　method　of　high-dynamic　actuator　based　in-situ　micro-forging　process　for　WAAM　was　proposed.　The　system　is　of　compact　design　and　has　the　characteristics　of　high　dynamic　response.　The　terminal　hammering　head　could　automatically　fits　the　surface　of　the　deposited　layer　successfully,　enabling　the　stable　control　of　the　real-time　hammering　force,　meaning　that　it　offers　a　solution　for　processing　deposited　layers　with　complex　paths.　In　addition,　the　terminal　hammering　head　could　be　sufficiently　close　to　the　molten　pool　to　enable　the　cumulative　rapid　micro-deformation　of　the　as-solidified　metal.　This　new　method　significantly　promotes　the　reduction　of　shrinking　holes　and　the　closure　of　spherical　pores　of　the　components.　The　microhardness　and　the　compressive　yield　strength　of　the　components　increased　by　12%　and　13%　respectively.　A　gradient　microstructure　was　obtained　due　to　the　transfer　of　strain.　The　mechanism　of　hybrid　dynamic　recrystallisation　induced　by　cumulative　rapid　micro-deformation　is　investigated.　These　promising　results　promote　the　possibility　of　applying　in-situ　micro-forging　technology　in　the　field　of　flexible　and　intelligent　manufacturing　in　aerospace.