The invention relates to an ultra-micro powder plant slice and a preparation method thereof. The preparation method comprises the steps that ultra-micro plant powder, outer margin fibers, an adhesiveand other additives are homogenized to form adhesive colloidal fluid, the adhesive colloidal fluid is extruded to form a slice shape, and drying formation is conducted. The plant slice is suitable fora heat-not-burn flavor-producing section, the plant slice is large in smoke formation amount, rich in fragrance and high in physiological satisfiability, the smoke flavor is close to natural plant fragrance, the product density and the filling value are close to those of natural plant leaves, the machining performance is high, and the amount of water required during production is small; no wastewater is generated, the raw material utilization rate is high, the plant slice meets the requirements for energy conservation and environment protection, the production technology is simple, and the preparation method is suitable for industrial production.