Electricity　enclosed　automobile　transmission　loaded　test-bed　control　system　with　high　rotating　speed,　large　scale　torque　and　high　accuracy　is　designed,　which　can　produce　positive　torque　and　negative　torque.　The　test-bed　can　be　used　to　simulate　transmission＇s　practical　work　condition.　Three　AC　motors　are　used　to　process　the　transmission＇s　driver　and　loading.　SIEMENS　S7-315　PLC　and　6SE70　inverter　are　set　up　as　the　controller　and　driver　respectively　in　the　two-level　control　system.　It　can　control　the　torque　of　input　shaft　and　output　shaft　of　the　tested　transmission,　and　the　dynamic　precision　of　speed　control　is±0.5%　and　the　accuracy　of　torque　loading　is±0.5%.　When　the　main　driving　motor　acts　as　a　driver,　and　the　loaded　motor　acts　as　a　generator,　the　loaded　energy　turns　into　power　energy　and　feedbacks　to　the　system,　which　not　only　saves　power　but　also　reduces　the　effect　to　the　outside　power　network.　The　results　showed　that　control　accuracy　achieves　the　expected　goal　and　the　use　of　electrical-closed　system　greatly　reduces　the　power　cost,　which　saves　about　75%　power　efficiency.