The invention discloses a cross-linked urea-formaldehyde resin organic delustering agent, as well as a preparation method and an application of the cross-linked urea-formaldehyde resin organic delustering agent. The preparation method comprises the following steps: mixing formaldehyde and urea according to mol ratio of 1.1-2.0, adjusting the pH value, raising the temperature to 60-80 DEG C, reacting for 1.5-4 h, discharging the materials to obtain prepolymer; using deionized water to dilute the prepolymer to 2-7 folds, adding metric acid, generating gel; crushing the gel product, adding the deionized water, adding diluted aqueous alkali under a stirring state, adjusting the pH value to 9-10, stirring, filtering and drying the substances, staying overnight, grinding by a ball mill to 1-30 microns; and filtering, drying and crushing the milled substances to obtain the cross-linked urea-formaldehyde resin. The urea-formaldehyde resin prepared by the method is free from formaldehyde release, can be used for leather water-based coating agent to promote the optical properties such as total light transmittance and matting effect, has good compatibility with matrixes such as polyurethane and acrylic ester, and can improve the mechanical properties such as coating layer surface scratch resistance.