The invention relates to the field of plant recycling, in particular to a technology for manufacturing pencil leads by waste plants. The pencil leads are prepared from the following components by weight ratio: 150-200 parts of plant raw material, 40-60 parts of flake graphite, 10-30 parts of a binding agent and 200-240 parts of water. The technology for manufacturing the pencil leads comprises the following steps: (1) heating the plant raw material to obtain an ash component; (2) grinding the flake graphite into fine powder, weighing the flake graphite powder together with the ash component and the binding agent, and then adding water into the weighed materials to obtain a mixture; (3) beating the mixture by a bar, and then carrying out extrusion molding; (4) after extrusion molding, enabling bar stock to enter a roasting furnace for roasting, and then enabling the product to enter a lead firing furnace for firing the leads; (5) carrying out oil immersion on the bar stock. After the technology is adopted, the bonding effect, breaking strength, wear resistance, writing smoothness and the like of the manufactured pencil leads are improved; furthermore, the cost is lowered, and the plant resources are reasonably utilized.