AF lens position determination systems and methods. The system comprises an anti-dazzling screen, a sensor and a processing module. The anti-dazzling screen comprises first and second areas. The length of a respective covered sub-area in the first area is a first distance, and the length of a respective uncovered sub-area in the first area increases progressively from the center to a first border of the anti-dazzling screen. The length of a respective uncovered sub-area in the second area is a second distance, and the length of a respective covered sub-area in the second area increases progressively from the center to a second border of the anti-dazzling screen. The sensor moves within a range, and generates high and low signals based on the anti-dazzling screen. The processing module determines the position of an AF lens according to the signals generated by the sensor.