With transport characteristics and experiment about molecular motor,an impact force model is established,which conforms Langevin equation.Kinetics of molecular motor transport is analyzed.Molecular motors could take stable stepping motion and effective transport in right impact force combined with noise intensity.Direction of motion of molecular motor is adjusted by direction of impulse force.Though average speed is not zero at different noise intensity,efficient transport of molecular motor ensemble indicates that the system is selective on noise intensity.Average speed of molecular motor ensemble decreases with increasing of load force,the motion even changes its direction as load force is great enough.