Abstract: Long spread spectrum code is applied in the Galileo system in order to improve the cross-correlation isolation ability. Longer spread spectrum code enlarges the search region which doubles the mean acquisition time when the single dwell strategy is adopted. The double-dwell strategy is proposed in this paper to optimize the system performance and the mean acquisition time is thus reduced up to 20 to 90 percent with given false alarm probability and detection probability. System simulation validates the strategy.