This study reports the significant pressure effect on the photocatalytic activity of hydrogen generation over two kinds of representative semiconductor catalysts (TiSi2 and Pt/TiO2). The photothermal-catalytic hydrogen generation from water steam splitting under visible light was achieved. And the physicochemical properties of the photocatalysts were characterized by XRD and XPS techniques. Compared to the conventional liquid-solid-phase photocatalytic method, this gas-solid-phase photothermal-catalytic method for hydrogen releasing from water steam exhibited a higher apparent quantum yield (22.01%) under the high pressure.