Materials with accurate and durable gas detection are essential for gas sensors. We developed a facile and effective method to deposit Pd onto WO3 nanosheets and used the samples for hydrogen gas sensing. The combination of the 2D ultrathin nanostructure of WO3 and the spillover effect of Pd enables a detection concentration down to 20 ppm of hydrogen and high selectivity against other gases including methane, butane, acetone, isopropanol, etc. Moreover, the durability of the sensing materials was testified through 50 cycles of exposure to 200 ppm of hydrogen. These outstanding performances are mainly attributed to a homogeneous and tenacious decoration of Pd on the surface of WO3 nanosheets, providing an attractive choice for practical applications.