The invention discloses a blade for a single-shaft shredding machine. The blade comprises a tool apron and a cutting edge, wherein the cutting edge is connected to the tool apron; the cutting edge is provided with a first cutting line, a second cutting line and a discharge groove, the first cutting line and the second cutting line are formed on the two sides of the cutting edge respectively, and the first cutting line is located in front of the second cutting line in the rotation direction of the blade; the discharge groove is formed between the first cutting line and the second cutting line and communicates with the end faces of the two sides of the cutting edge; and the tool apron is provided with installation holes. According to the blade for the single-shaft shredding machine, the cutting edge can carry out cutting for two times every time a cutter shaft rotates by one circle, the cutting force is great, material with high hardness can be crushed easily, the energy consumption is reduced on the condition of the same material, the material is prevented from being left on a cutting knife body, and the cutting process is smooth. In addition, the tool apron is provided with the installation holes, the blade can be fixed to the cutter shaft by connecting connectors such as plug pins and bolts into the installation holes in a penetration mode, and replacement is convenient.