At　present,　the　in-situ　forging　devices　do　not　have　the　ability　to　flexibly　adjust　impacting　forces　over　a　wide　frequency　range　and　cannot　be　easily　integrated,　which　restricts　its　application　on　DED-arc　(directed　energy　deposition-arc)　technology　for　additive　manufacturing.　A　novel　method　and　system　of　in-situ　micro-impacting　assisted　DED-arc　based　on　a　compact　high-dynamic　linear　actuator　was　proposed,　developed　and　verified　in　arc　deposition　of　5B06　aluminum　alloy.　The　terminal　impacting　head　could　be　sufficiently　close　to　the　molten　pool　to　enforce　the　obtaining　of　flat　surface　of　the　deposited　layer.　The　results　show　that　the　in-situ　micro-impacting　could　produce　accumulating　rapid　micro-deformation　and　thus　induce　a　gradient　microstructure.　DDRX　(discontinuous　dynamic　recrystallization)　and　CDRX　(continuous　dynamic　recrystallization)　hybrid　dynamic　recrystallization　behavior　was　observed.　The　microhardness　of　impacted　samples　was　increased　by　9.5　%　and　8.0　%　in　vertical　and　horizontal　direction,　respectively.　The　process　of　rapid　micro-deformation　contributes　to　the　retaining　of　the　in-situ　work-hardening　effect　at　high　temperatures,　which　made　the　proposed　in-situ　impacting　method　a　preferred　option　for　DED-arc　additive　manufacturing.