A light detection method for a light detection device is provided. The light detection device includes multiple scan lines and multiple light sensing elements. Each of the light sensing elements is coupled to a corresponding one of the scan lines. The light detection method includes: in a detection mode, sequentially scanning a first scan line to a (N+1)th scan line among the scan lines, wherein a Nth scan line is not adjacent to at least one of a (N−1)th scan line and the (N+1)th scan line; reading signals of the light sensing elements coupled to the first scan line to the (N+1)th scan line; determining whether the signals meet an exposure standard; and controlling the light detection device to enter a value reading mode when the signals meet the exposure standard.