A sensing element for electromagnetic wave detection, electrical radiography imaging system applying the element and method thereof is provided. The sensing element may include a substrate, an active component on the substrate, a plurality of first electrodes on the substrate, a plurality of second electrodes on the substrate, a first blocking layer, a photo-conversion layer on the first blocking layer, and a third electrode on the photo-conversion layer. The plurality of first electrodes is coupled together. The plurality of first electrodes is interlaced with the plurality of second electrodes and is coupled together. The first blocking layer is on the active component, the plurality of first electrodes, and the plurality of second electrodes. The photo-conversion layer is for absorbing electromagnetic wave transmitted through an object being imaged by a radiography imaging system and generates electric charges collected by the plurality of first and second electrodes, and the third electrodes.