Abstract: A novel scheme of dual track surface acoustic wave SO₂ gas sensor based on WO₃（Tungsten trioxide） films is proposed.Utilizing Tungsten powders,H₂O₂,CH₃OH and PVP as raw materials and pyrogenation spray method,micro-porous networks WO₃ film is fabricated in measure acoustic track of dual track surface acoustic wave device.The SO₂ gas sensor using dual track surface acoustic wave device based on WO₃ films would absorb and desorbed SO₂ gas in physical method under normal temperature.Because the dual track receiving structure is incorporated into the sensor,the environment disturbance quantities for measurement signal are eliminated,and the reliability and veracity are further improved.Experiments results confirm that the dual track surface acoustic wave SO₂ gas sensor based on WO₃ films is endowed with better reproducibility,and excellent response performance for different concentration SO₂ gas in the measurement range,and the linearity sensitivity reaches to 6.8 KHz/ppm from 0.5ppm to 20ppm.