The invention refers to a method and device for monitoring brake lining wear and air clearance of an operating brake in motor vehicles, especially in commercial vehicles. Each wheel brake is provided with at least one displacement transducer which marks brake lining wear and air gap of service brake by means of an evaluation unit. A warning indicator is activated, when the detected air gap is larger or smaller than the predetermined air gap. According to the utility model, the displacement transducer and the evaluation unit are designed to obtain a current gap as an actual gap according to evaluation of signal difference of the displacement transducer under the case of controlling or not controlling the brake so as to obtain each difference between a gap and a rated gap, wherein the warning signal is activated when limits obtained by a specified rated gap exceed or the gaps is too large accordingly and when limits obtained by a specified rated gap is lower or the gaps is too small or no gap exists accordingly.