Puts forward a Automatically Gain Adjustinge Fast Intelligent Tracking (AGAIT) algorithm, realize quick automatic accurate location to the goal, especially for the weaker signal. With the change of the size, location and output signal of the goal in four quadrant detector, the linear probe interval is determined in the four quadrant detector. In this interval, a liner relation can be get between the spot position and the corresponding output signal. The target quick location is realized with this relation. The sum of the four quadrant detector output is sampled in real-time, it is related to the sensor's signal strength, then the change rate of the signal strength can be get, using adaptive learning ways to get the change trend of signal strength, and realized dynamic adjustment of the signal gain, in order to improve the signal resolution ratio when signal is weak, the tracking accuracy can be improved with this way. The experimental data show the algorithm can rapidly locate position in the linear interval and accurately track through the dynamic change signal gain for the weaker signal. In this way, the tracking precision can be improved to 1.08%.