There was an increasing research into developing microcantilever sensor in the biochemical, chemical and material research fields.Microcantilever array designed and used for sensing was the important direction in this research field. In this paper, an optical sequential illumination technique has been developed for real-time monitoring of the deflections of microcantilever arrays for sensing application. The technique based on the two lasers were vertical put by the side of the beam splitter prism and laser beams shaded in turns with cardboard rotated by the stepping motor. The individual signals of the deflection from cantilever tip measured by one position sensitive detector. This platform applied for real-time recording of adsorption of mercatoundecanoic acid in an aqueous solution by using an array of two microcantilevers. The experimental results pointed out: the signals of two lasers beam can be separated by using mathematics method. This new method can provide an easy way to integrate and realize sensor of two microcantilevers and to design on the microcantilever array based optical lever. Further, these characteristics make this method appealing for explosive detection for research.