As　lightweight　requirements　rise　in　transportation,　aerospace,　and　other　industries,　magnesium　alloys　have　a　great　application　prospect.　However,　the　low　formability　capabilities　of　magnesium　alloys　lead　to　a　severe　limit　in　applications.　At　present,　there　are　many　reports　on　the　influences　of　texture　and　second　phases　on　the　formability　of　magnesium　alloys　at　room　temperature.　Nevertheless,　the　dominant　factors　affecting　the　formability　performance　of　magnesium　alloys　at　room　temperature　are　not　clear.　In　this　study,　the　development　of　the　microstructures　and　texture　of　Mg-xZn-0.5Er　(x　=　0.5,　2.0,　3.0,　4.0,　mass　fraction,　%)　alloy　sheets　were　studied,　and　the　impact　of　the　texture　and　second　phases　on　the　formability　of　these　sheets　were　also　investigated.　The　findings　showed　that　the　increase　in　Zn　addition　led　to　an　early　and　complete　dynamic　recrystallization　(DRX)　in　Mg-Zn-Er　alloys　sheets,　and　these　recrystallized　grains　would　expand　significantly　during　subsequent　hot　rolling　processes.　These　recrystallized　grains　with　a　large　size　were　typically　elongated　and　then　helped　to　create　a　strong　basal　texture.　Thus,　it　was　discovered　that　the　microstructures　of　these　sheets　were　typically　made　up　of　equiaxed　and　elongated　grains.　The　formability　performance　of　these　sheets　was　strongly　related　to　the　size　of　the　second　phases　and　the　texture.　The　formability　of　the　sheets　containing　microscopic　second　phases　mainly　depended　on　the　basal　texture,　while　the　formability　of　the　sheets　which　contained　coarse　second　phases　was　mostly　influenced　by　the　second　phases　and　basal　texture.　Particularly,　when　the　component　of　the　coarse　second　was　larger,　the　formability　would　get　more　inferior　due　to　the　predominant　role　of　the　second　phase　at　room　temperature.