The invention discloses a five-coproduction process for comprehensively utilizing biological straw, aiming at solving the technical problem of expanding the straw utilization scale. The process consists of three lines: the first line is used for producing xylooligosaccharide: smashing biological straw, introducing steam for boiling, passing through an ultrafiltration membrane-1 after filter pressing, passing through an ultrafiltration membrane-2 after enzymatic hydrolysis reaction, enabling penetrating fluid to be subjected to nanofiltration concentration so as to be concentrated by 3-5 timesto obtain the xylooligosaccharide; the second line is used for producing straw pulp and sodium lignosulfonate: smashing the biological straw, enabling the smashed biological straw and waste residue tobe subjected to pressurized high temperature boiling together, enabling obtained serous liquid to be subjected to filter pressing separation, and enabling solid matter obtained after separation to besubjected to adverse current cleaning to obtain wheat straw pulp; enabling black liquor and washing black water obtained after separation to evaporate and concentrate, then performing heat exchange via hot-blast air to obtain sodium lignosulphonate powder; and the third line produces biochar and combustible pyrolysis gas. On the premise of generating remarkable economical benefit, the five-coproduction process is friendly to environment and does not generate waste water so as to achieve zero discharging, solid waste does not exist, and the exhaust gas reaches the standard and is emitted.