The invention discloses in-situ small-underground-chamber mounting equipment of a tunnel shield. The equipment comprises a crossbeam, a traveling mechanism, hydraulic telescopic support legs and hingedevices, wherein lower ends of the hydraulic telescopic support legs are mounted on the traveling mechanism, upper ends of the hydraulic telescopic support legs are hinged to ends of the crossbeam through the hinge devices, the traveling mechanism is placed on a track, which is laid on the ground of a small underground chamber and extends back and forth, two slider type crane jibs are mounted onthe crossbeam in a suspended manner and are jointly used for hoisting the tunnel shield, the hydraulic telescopic support legs are equipped with jacking cylinders and hydraulic locks, and the slider type crane jibs are equipped with transverse moving cylinders and hydraulic locks. Simultaneously, the invention further discloses a mounting method for carrying out tunnel shield in-situ small-underground-chamber mounting by using the in-situ small-underground-chamber mounting equipment of the tunnel shield. The equipment has the characteristics that the lifting capacity is large, the outline dimension is small and a working place can be quickly switched, and is very application to TBM (Tunnel Boring Machine) assembling operation in small underground chambers or a variety of originating tunnels, then, the construction period can be shortened, the total cost is reduced; the equipment is safe and reliable, and human resources are saved.