The cross interference in motions of optical pickup actuator is the key factor to affect the dynamic characteristics and quality of optical spot. Because of the shortcomings of single DOF resonant model of actuator, the 3-DOF kinetic model for 2-D actuator is set by 2nd Lagrange equation. The effective focusing and tracking motions, the coupling between focusing and tracking motions and the characteristics of rolling interference motion are described by this model. It also reflects the quantitative influence of the inconsistency of actuator's four key points on dynamic characteristics. Experim...