An optical detection method of a photo-alignment LCD panel includes steps: A. generating a model image according to an internal image of a qualified prearranged detection unit of a photo-alignment LCD panel; B. generating an image by obtaining an internal image of the detection unit of the photo-alignment LCD panel to be inspected using a unit of the prearranged detection unit. The method further includes comparing the image with the model image and generating a comparison result according to the comparison. In the present disclosure, the prearranged detection unit is used as a reference comparison unit. The internal image of the detection unit is added into the model image.