Here　we　report　in-situ　TEM　observations　on　interaction　between　dislocations　and　beta＇　phases　in　aged　Mg-Gd　alloys.　The　slipping　＜　a　＞　dislocations　squash　into　the　interface　and　bow　out　to　bypass　the　beta＇　phase,　leading　to　a　zigzag　route　of　plastic　flow.　Orowan　mechanism　is　determined　as　the　main　strengthen　mechanism.