Based　on　the　principle　of　electrothermal　actuator,　this　paper　designs　a　new　type　of　electrothermal　micro-flat　lens　unit　structure　to　micro-adjust　the　phase　of　the　transmitted　beam.　This　structure　mainly　consists　of　a　micro-flat　lens　and　four　symmetrical　S-shaped　actuators.　The　lens　can　realize　two　motion　states,　vertical　displacement　and　tilting,　by　applying　voltages　to　different　actuators.　Symmetry　of　actuators　avoids　the　influence　of　ambient　temperature　on　the　tilt　of　the　lens.　A　positive　hexagonal　shape　of　lens　provides　a　foundation　for　relevant　dense　array　structure　with　a　high　filling　factor.　The　natural　frequency,　displacement　and　tilting　of　the　structure　are　simulated　by　COMSOL.　Results　show　that　the　electrothermal　micro-flat　lens　unit　structure　can　work　normally　lower　than　5806.8　HZ,　and　get　a　large　vertical　displacement　of　166　μm　and　a　tilt　of　12°　at　a　low　driving　voltage　of　1.8　V.　©　2024　IEEE.