A method and apparatus for detecting crystal orientation of a silicon wafer is proposed. The detection method uses a camera shooting device to irradiate the silicon wafer in a rotation manner in different angular directions and obtains the corresponding reflection intensities, based on which a reflection curve is drawn for a grain of interest in a polar coordinate system; normal directions of three or more faces of a regular octahedron of a grain are determined by identifying a pixel brightness extreme value in the reflection curve, and then all normal vectors of the regular octahedron are calculated, so that a crystal orientation of the grain of interest may be calculated. The camera shooting device has a light source and one or more camera shooting probes.