An apparatus for continuously processing a lignocellulosic material by using of a single-stage or two-stage pretreatment processing with related to the acid-catalyzed steam explosion processing combined with dilute acid hydrolysis and steam explosion, in which parameters are adjusted to maintain in a state where lignocellulosic material feeding, acid mixing pre-heating, dilute acid hydrolysis reaction, steam explosion and flash discharge, to solid and liquid separation are simultaneously and continuously operated, so as to achieve in the results of acquiring xylose hydrolyzate by hydrolyzing hemicellulose, destroying lignocellulosic material structure, increasing surface area and porosity.