Start-up working condition is the key to the research of optimal engagement of auomaticclutch for AMT. In order to guarantee an ideal dynamic performance of the clutch engagement, anoptimal controller is designed by considering throttle angle, engine speed, gear ratio, vehicle accelera-tion and road condition. The minimum value principle is also introduced to achieve an optimal dy-namic performance of the nonlinear system compromised in friction plate wear and vehicle drive qual-ity. The optimal trajectory of the clutch engagement can be described in the form of explicit and ana-lytical expressions and characterized by the deterministic and accurate control strategy in stead ofindeterministic and soft control techniques which need thousands of experiments. For validation of thecontroller, test work is carried out for the automated clutch engagements in a commercial car with antraditional mechanical transmission, a hydraulic actuator, a group of sensors and a portable computersystem. It is shown through Start-up working condition is the key to the research of optimal engagement of auomatic clutch for AMT. In order to guarantee an ideal dynamic performance of the clutch engagement, an optimal controller is designed by considering throttle angle, engine speed, gear ratio, vehicle accelera- tion and road condition. The minimum value principle is also introduced to achieve an optimal dy-namic performance of the nonlinear system compromised in friction plate wear and vehicle drive qual- ity. The optimal trajectory of the clutch engagement can be described in the form of explicit and ana-lytical expressions and characterized by the deterministic and accurate control strategies in stead of in deterministic and soft control techniques which need thousands of experiments. For validation of thecontroller, test work is carried out for the automated clutch engagements in a commercial car with antraditional mechanical transmission, a hydraulic actuator, a group of sensors and a portable computer system is shown through