Automatic mechanical transmission (AMT) bed testing is one of the important jobs for AMT researching and development. Through bed testing we can finish many works such as testing performance of AMT, AMT-engine matching, optimizing control rules and so on. AMT testing bed is built up base on the sample AMT developed by ourselves. Data are transmitted between PC and SCM though RS232 COM. By this way electronic throttle, clutch and shifting are controlled. Hardware port can be read in Windows 2000 by calling the unpublicized functions. Testing-controlling Program is also developed and AMT bed testing can be carried out with advanced test and control technology.