Aiming to the problem that traditional nonlinear filters have bad robustness for abrupt state change system, the tracking is slow and even becomes invalid, Strong Tracking seventh-degree Cubature Quadrature Kalman Filter(ST-7thCQKF) is proposed. The algorithms fuses seventh-degree Cubature Quadrature Kalman Filter(7thCQKF), which shows good filtering effect for nonlinear system, with Strong Tracking Filter(STF), the tracking precision of abrupt state change system is improved through introducing fading factor into the prediction error covariance of 7thCQKF to adjust the gain matrix in filter process. The simulation and experiment results show that, ST-7thCQKF can well deal with the problem of state tracking for system with abrupt state.