The invention is a kind of sizing ring light beam differential confocal sensor with high spatial resolution. It includes laser device, beam expanding device, pin hole, ring light sizing device, adjustable light conjunction, polarized beam splitter, 1 / 4 wave piece, tracing inductance sensor, measuring lens, the beam splitter, collecting mirror, pin hole and two photoelectric detector behind the two holes. The invention combines the optical hyper resolution and differential confocal micro trancing technology, in order to enhance the resolution and the range of the sensor; it caters the demands of high spatial resolution, high accuracy, and large measuring range. Especially applies to the measurement of tiny structure, micro stage, tiny grooves, line width and the surface shape.