Ordered mesoporous Ag₂O/SnO₂was synthesized via nanocasting method using hexagonal mesoporous SBA-15 as template. As-prepared Ag₂O/SnO₂samples were characterized by X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray photoelectron spectroscopy. A microspheric directly heated gas sensor based on the mesoporous Ag₂O/SnO₂was fabricated, and its gas sensing performance was investigated. Results indicated that the sensor based on mesoporous Ag₂O/SnO₂exhibited excellent selectivity, high response, and good stability to H₂S at 100℃. A pulse-driving method was then introduced to enhance the sensitivity to H₂S. Under pulse-driving, the response of the sensor to 300 ppb H₂S was 5.7, which was approximately two times higher than that under constant current, and the limit of detection was improved to 50 ppb. The high-sensing performance of the sensor was attributed to the composition and structure of mesoporous Ag₂O/SnO₂and the pulse-driven mode.