Photocatalytic biorefinery synchronously assisted hydrogen evolution is promising, but limited research has been implemented. Here, the biorefinery-assisted ultra-high hydrogen evolution photocatalyzed by black phosphorus sensitized carbon nitride (BP-s-CN) was achieved. The BP-s-CN was prepared by ultrasonic-assisted assembly and freeze-drying of a mixture of CN and 2D BP. It was proved that the interfacial interaction between 2D BP and CN significantly improves the visible light utilization of CN and accelerates the separation of photo-induced carrier. The BP-s-CN displays ultra-high hydrogen release rate of 1.45 mmol h−1 with the best lactic acid yield (74.4%). Just 4.0 at% BP addition increases hydrogen yield by 4.8 times. The BP-s-CN photocatalytic system is also applicable to different biomass-based monosaccharides, and pentoses were more appropriate to produce lactic acid than hexoses. Interestingly, among of h+, O2−, OH, and 1O2, the O2− played a major role for lactic acid production.