This invention relates to a kind of surface parameters measuring instrument to measure multi-kinds of parameters for magnetic discs disc slice in high precisions, belongs to the technical domain jof measuring instruments. Said invention utilizes a laser heterodyne non-contact measuring method to realize the measurement of the geometrical parameters of the disc slice of a magnetic disc. Said instrument uses a pneumatic-floating guide rail to drive an oplic sensor into diametric feeding motion and uses a pneumatic floated axle bearing to drive the measured magnetic disc slice into revolving motion. When the disc slice measured relative to the optic sensor is making turning around motions perpendicular with the plane of the measuring axle, the optic sensor is making diametrical motion along the guiding roils, also making diametric seanning against the disc slice, at this time information of the whole disc slice may be obtained. Said measuring instrument may made measurement of disc slice.