The invention discloses a method for preparing a lignin urea-formaldehyde pesticide microcapsule. According to the invention, the method comprises the following steps: taking modified lignin, formaldehyde and urea as a monomer, forming a water-soluble performed polymer under base catalysis, diluting and forming continuous phase, forming dispersed phase by pesticide, an organic solvent and a surfactant, mixing and stirring the continuous phase and the dispersed phase to form an oil-in-water emulsion, performing in situ condensation polymerization under the acidic condition, heating and solidifying, pumping filtration and washing, drying to obtain the solid microcapsule particles. The modified lignin is obtained by formaldehyde hydroxymethyl modification of the industrial grade wheat straw soda lignin. According to the invention, the waste wheat straw soda lignin in paper industry is taken as the main wall material, so that the production cost of the microcapsule can be effectively reduced and the resource utilization of waste biomass can be realized. The preparation method of the invention has the advantages of simple process, rapidity and controllable microcapsule particle size, and is capable of realizing the industrial production, increasing the pesticide utilization rate, prolonging the persistent period, minimizing the environmental pollution in the process of agriculturalproduction, reducing the agriculture production cost and the like, and has good market prospect.