A method and a measuring system for determining the surface condition on a rail head along a laid railway track formed by rails uses a measuring carriage and a measuring unit with at least a first measuring arrangement. The first measuring arrangement includes a measurement base carrier, a guide arrangement, and at least one first sensor located on the measurement base carrier. The measurement base carrier is guided in a movable manner relative to the carriage frame by the guide arrangement in a normal alignment with respect to a rail plane defined by one of the respective rails. Furthermore, the measurement base carrier including the at least one first sensor is mechanically supported on at least one of the rails by a supporting device during displacement of the measuring carriage, and is thus constantly guided at a predetermined, fixed distance above the rail.