A　two-speed　transmission　for　electric　vehicles　is　designed,　which　comprises　of　two-stage　epicyclical　gear　sets　without　outer　ring　gears,　a　brake　band　and　a　dry　fiction　clutch.　The　proposed　system　allows　a　seamless　shifting　between　any　two　speeds　in　an　electric　vehicle.　Taking　8m　electric　bus　as　example,　do　the　parameters　matching　for　drive　system.　Based　on　the　simulation　for　the　dynamic　of　the　electric　bus,　the　result　demonstrates　the　dynamic　performance　of　the　electric　bus　perfectly　meets　the　need　of　the　design　target.　To　further　prove　the　effectiveness　of　the　drive　system　with　proposed　two-speed　transmission,　a　bench　test　and　a　real　driving　cycle　on　electrical　bus　are　developed.　It　is　shown　experimentally　that　the　proposed　SDAT　method　demonstrates　a　higher　efficiency　and　shifting　comfort　when　compared　to　the　automated　manual　transmission　with　same　transmission　ratio.