This　paper　presents　a　comprehensive　modal　analysis　of　Z-shaped　beam　electrothermal　microactuators　for　the　first　time.　Both　longitudinal　and　lateral　vibrations　are　taken　into　account　to　obtain　the　vibration　equations　of　the　unique　geometric　feature:　a　Z-shaped　beam　with　a　shuttle　in　the　middle.　The　natural　frequencies　and　the　associated　mode　shapes　of　the　Z-shaped　beams　are　calculated　based　on　the　vibration　equations　subjected　to　both　boundary　and　continuity　conditions.　Finite　element　simulations　are　performed　using　ANSYS　software　to　verify　the　analytically　calculated　natural　frequencies　and　mode　shapes　of　the　Z-shaped　beams.　Based　on　the　modal　analysis,　this　paper　also　investigates　the　relationship　between　the　natural　frequencies　and　volume　scale　of　the　Z-shaped　beam　electrothermal　microactuators.　In　addition,　comprehensive　parameter　analysis　is　conducted　to　provide　insights　and　guidance　on　designing　and　optimization　of　the　Z-shaped　beam　electrothermal　microactuators.