To investigate the influence of dynamics interaction between the driver body and miniature automobile, the driver model was connected to the miniature automobile with spring-damping elements. A handling stability dynamics model was constructed for the driver-vehicle system with 6 degree of freedom (DOF). Based on the parameter identification for stiffness and damping coefficients at human-seat interface, the numerical method was used to solve the handling stability dynamics model by Matlab/Simulink. The influences of human-vehicle dynamics interaction on the stable and transient responses of step steering were analyzed for the miniature automobile with different curb weight. Results show that the human-vehicle dynamics interaction affects the roll response obviously, and increases the steady stable values, peak values and overshoot. With the curb weight and size more and more close to the driver body, the influences will be more significant. The human-vehicle dynamics interaction has a little effect on the yaw rate, increases the tendency of understeering and enlarges the fluctuation of the yaw rate curve.