For　electrically　driven　commercial　vehicles　equipped　with　three-speed　automatic　mechanical　transmission　(AMT),　the　transmission　control　unit　(TCU)　without　vehicle　mass　and　road　gradient　estimation　function　will　lead　to　frequent　shifting　and　insufficient　power　during　vehicle　full-load　or　grade　climbing.　Therefore,　it　is　necessary　to　estimate　the　mass　and　road　gradient　for　the　electrically　driven　commercial　vehicles　equipped　with　the　three-speed　AMT,　and　to　adjust　the　shift　rule　according　to　the　estimation　results.　Given　the　above　problems,　this　paper　focuses　on　the　control　and　development　of　the　electrically　driven　three-speed　AMT　and　takes　the　shift　controller　with　the　vehicle　mass　and　road　gradient　estimation　as　the　research　goal.　The　mathematical　model　and　simulation　model　of　vehicle　dynamics　are　established　to　verify　the　shift　function　of　TCU.　The　least　squares　method　and　calibration　techniques　are　applied　to　estimate　the　vehicle　mass　and　road　gradient.　According　to　the　estimation　results,　the　existing　shift　strategy　is　optimized,　and　the　software-in-the-loop　simulation　of　the　transmission　controller　is　carried　out　to　verify　the　function　of　the　control　algorithm　software.　The　hardware-in-the-loop　test　model　is　established　to　verify　the　shift　strategy＇s　optimization　effect,　which　shortens　the　controller＇s　forward　development　cycle.　According　to　the　estimation　results　of　mass　and　gradient,　the　error　result　of　the　proposed　method　is　controlled　within　4.5%　for　mass　and　8.6%　for　gradient.　The　experiment　verifies　that　the　optimized　shift　strategy　can　effectively　improve　the　dynamic　performance　of　the　vehicle.　The　HIL　experimental　results　show　that　the　vehicle　can　maintain　low　gear　while　climbing　the　hill,　and　the　vehicle　speed　does　not　decrease　significantly.