2,4,6-trinitrotoluene (TNT) has a strong explosive force and environmental toxicity, with the increasing threat of terrorist attacks worldwide, the high sensitivity detection of nitroaromatic explosives has become an urgent problem to be solved, and now the commonly used detection method is to use the optical principle, combined with large and expensive equipment to detect it. In order to detect the content of TNT in bad environment quickly and in real time, surface acoustic wave technology was proposed to detect different concentrations of TNT. In this paper, an ultra-sensitive TNT sensor was fabricated based on the surface acoustic wave technique. Specific detection of TNT was achieved by recognizing the shift of resonance frequency. Moreover, the whole process for the detection was done in 30 min, dedicating the rapid/real-time application of the sensor. This study focused on the transfer characteristics of resonance frequencies at different concentrations. The frequency of surface sound waves varies greatly at high concentration because the modified IDT (interdigital transducers) electrodes were utilized, which is easy to work under different concentrations of TNT. The proposed sensor has the advantages of real-time, simple and convenient detection, which provides a valuable method for the real-time detection of TNT.