Many unbalance related vibration phenomena can not reasonably explained by rotor isotropic hypothesis theory. Based on the anisotropic characteristics of stiffness and damping in rotor system, the dynamic model of the nonlinear stiffness and damping rotor system was set up. Then the unbalance response of system was solved by fourthorder Rungekutta method. The effect of stiffness variation in the two vertical directions on all parameters of full vector spectrum was studied with different nonlinear stiffness coefficients. The results show that: stiffness variation has strong regularity influence on vibration vectors, ratio of vibration vectors and the azimuth angle at a constant revolving speed. This conclusion provides a theoretical reference for application of the full vector spectrum technique in the nonlinear factors. 