The invention discloses a flame-retardant urea-formaldehyde resin adhesive which contains the following raw materials in parts by weight: 40-60 parts of formaldehyde, 120-140 parts of urea, 2-3 parts of polyvinyl alcohol, 5-7 parts of melamine, 0.2-0.4 parts of sodium myrastate, 2-4 parts of decabromodiphenyl ethane, 1-2 parts of ammonium dihydrogen phosphate, 0.6-1 part of tricresyl phosphate, 2-3 parts of tackifying aid, 0.1-0.3 parts of calcium acetylacetonate, 0.3-0.5 parts of 3,2-thiolbenzimidazole, 0.4-1 part of sodium dimercaptosulphonate and 0.1-0.3 parts of silane coupling agent KH560. According to the invention, formaldehyde, urea, melamine and aids are blended and modified, the finished product has good crosslinking property, stable structure, perfect water resistance, anti-aging property, flame retardance and the like and long service life; and the added tackifying aid can be effectively combined into a copolymer adhesive molecular network, so that the tackiness and the biodegradability and disintegration of subsequent products are enhanced, and the comprehensive performance is excellent.