The invention discloses a vehicle-mounted hydraulic trolley for tunnel excavation supporting. The vehicle-mounted hydraulic trolley comprises main benches (3), and is characterized in that at least two layers of main benches (3) are arranged, the main bench (3) at the bottom layer is installed on a trailer of a vehicle through lifting hydraulic oil cylinders (5), the main benches (3) at the upperlayers are stacked through hydraulic telescopic rods (7), cantilever benches (4) are installed on the two sides of the main benches (3), and the cantilever benches (4) are controlled to expand and contract in the horizontal direction through telescopic hydraulic oil cylinders (6). By using a power system of a self-propelled vehicle, the trolley can freely travel to an excavation supporting workingface to be in place, be supported stably, extend the benches and withdraw from the field. The vehicle-mounted main benches and the cantilever benches are used as operation platforms, and the main benches and the cantilever benches can be freely lifted and lowered and extended to the two sides for adjustment correspondingly by using a hydraulic system, so that the benches can be adjusted accordingto the section size of a tunnel and can be freely adjusted to a suitable position of the excavation supporting working face, and tunnel excavation supporting construction is carried out.