The invention discloses a phenolic resin adhesive and a preparation method thereof. The phenolic resin adhesive consists of the following components in parts by mass: 30-50 parts of phenolic resin, 6-10 parts of a polyacrylate salt, 7-11 parts of tricresyl phosphate, 20-40 parts of epoxy resin, 6-8 parts of acetone, 10-12 parts of ethanol, 1-3 parts of a cross-linking reinforcing agent, 4-6 parts of polyorganosiloxane, 2-4 parts of silane coupling agent, 16-18 parts of asbestos powder, 10-15 parts of natural latex and 3-4 parts of an anti-aging agent. By adopting the phenolic resin adhesive, the production cost of a phenolic resin type adhesive can be lowered, the comprehensive quality and the effect of an adhesive can be improved, and plywood made by using the adhesive in a pressing molding manner is relatively good in bonding quality.