This　paper　presents　the　working　theory　and　fabrication　of　a　micromechanical　electromagnetic　relay　based　on　MEMS　technology.　The　magnetic　circuit　system　of　the　microrelay　consists　of　the　lower　magnetic.　circuit,　a　planar　spiral　coil,　a　fixed　contact　and　a　movable　contact.　Compared　to　the　traditional　relay,　a　planar　coil　is　substituted　for　a　solenoid　coil　and　favor　of　the　CMOS　planar　fabrication.　The　relay　size　of　about　5mm　x　5mm　x　0.4mm　is　fabricated　using　the　common　micromachining　technology　like　lithography,　electroplating　as　well　as　sacrificial　layer　etching.　Theoretical　calculations　are　also　carried　out　with　respect　to　the　electromagnetic　forces　yielded　by　the　exciting　coil　using　the　magnetic　circuit　model.　In　addition,　the　primary　testing　results　of　the　microrelay　are　given.　The　coil　resistance　of　the　microrelay　is　about　160Omega.　When　the　current　is　50mA　through　the　coil,　the　movable　contact　can　complete　the　pull-on　action.　The　conducting　resistance　of　the　microrelay　is　about　1.7Omega　after　pull-on.