The invention discloses a method for preprocessing and reclaiming lignocellulose and a device of the method, wherein the method comprises: installing the lignocellulose into a recycle reactor, injecting hydrochloric acid, opening a circulating pump to carry out cyclic reaction under the temperature of 50DEG C-200DEG C, adding chloride salt into hydrolyzate which is obtained after the reaction is finished and heating, absorbing HCI which is volatilized and water vapour which is generated by negative pressure which is produced by a Venturi tube that water currents flow through, reclaiming the HCI in the hydrolyzate through flowing circularly, and using the hydrolyzate after acid-removing to ferment. The method of the invention can effectively increase the conversion rate of hemicellulose, the removal rate of lignin and the conversion rate of cellulase hydrolysis in the lignocellulose, fermentation inhibiting products are reduced, the energy consumption is lowered, the using amount of the cellulase is reduced, the sugar concentration is increased, simultaneously, the HCI can be reclaimed and utilized, the problem of environmental pollution is solved, and simultaneously matching between the sugar concentration and the fermentation concentration is further increased.