The invention provides a method for determining the layer type of a blu-ray disk. First, a laser beam is focused on a target layer of the blu-ray disk. Reflection of the laser beam from the target layer is the detected to obtain a reflection signal. The reflection signal is then processed to generate a first tracking error signal and a second tracking error signal. Magnitudes of the first tracking error signal and the second tracking error signal are then measured. The magnitude of the second tracking error signal is then subtracted from the magnitude of the first tracking error signal to obtain a difference value. Finally, the layer type of the target layer is determined by comparing the difference value with the first predetermined threshold.