The utility model relates to a non-contact bore linearity measuring apparatus which comprises a light source, a photoelectric sensor and an air floatation platform, wherein light emitted by the light source irradiates on the photosensitive surface of the photoelectric sensor installed on the center of the air floatation platform, and the air floatation platform is installed in a bore of a measured piece through a central support and is movable in the bore of the measured piece. The non-contact bore linearity measuring apparatus is simple in structure, and high in automation level, sensitivity and stability. The measuring result is highly precise, and the precision reaches to a micron order.