State estimation method and feedback control method are the keys of high precision time and frequency steering algorithm. The paper presents a time and frequency steering algorithm based on linear quadratic Gaussian control combined state estimator with optimal feedback controller effectively. By analyzing the noise characteristics of crystal oscillator, a receiver clock state model is established, and the extended Kalman filter is designed to estimate and predict the clock and frequency offsets of the receiver. The optimal feedback control makes the clock and frequency offsets converge to zero quickly and stably. The experimental results of a GNSS receiver with constant temperature and voltage controlled crystal oscillator show that, the algorithm can improve the accuracy of the receiver time and frequency standards by one or two orders of magnitude, compared with the commonly used Kalman estimator and direct feedback controller time and frequency steering algorithm.