In this letter, a quartz-enhanced photoacoustic spectroscopy (QEPAS) gas sensor based on a single off-beam acoustic micro-resonator (AmR) and dual quartz tuning forks (QTFs) was demonstrated for the first time. The sensor offers advantages of compact sensing structure and high acoustic energy utilization efficiency. The key parameters of designed off-beam AmR were optimized based on standing wave enhancement characteristics. Water vapor (H₂O) in the environment was chosen as the target gas to investigate the sensor performance. Under identical experimental conditions, the reported sensor achieved 15.02 times improvement in detection sensitivity compared to the bare QTF based sensor system, as well as a 1.53 times enhancement over the traditional off-beam QEPAS technique.