Since its discovery in 1985, Kinesin has attracted extensive interests about its biologic role in cell living. However, it is still a question how kinesin converts chemical energy from ATP hydrolysis to mechanical energy for the movement of cargo. Our hypothesis is that kinesin works through dynamic conformations, which are difficult to capture with x-ray crystallography and electron microscopy. using an advanced simulation method, the self-guided Langevin dynamics (SGLD), we discovered that kinesin has a highly dynamic microtubule binding interface (MTBI). In aqueous solutions, kinesin extends the MTBI motif and forms an extended conformation. In kinesin-microtubule complexes, kinesin has a dynamic conformation and can convert to the extended conformation at high energy levels. Based on these discoveries, we proposed the conformation-extension mechanism for motor proteins. This mechanism opens a new view of motor proteins and explains well many experimental observations.