The invention provides a phenolic foam heat insulation board and a production method thereof. The heat insulation board comprises 70-80 parts of phenolic resin, 5-10 parts of modified nano-silica, 4-8 parts of a toughening agent, 3-6 parts of a surfactant, 10-15 parts of a curing agent and 4-8 parts of a foaming agent. The production method comprises the following steps: 1, preparing the modified nano-silica: dissolving nano-silica in ethyl acetate, carrying out water bath heating to 40-60 DEG C, adjusting the obtained solution to 8-9 by using ammonia water, adding a silane coupling agent, carrying out a reaction for 18-24 h, and carrying out centrifuging and washing to obtain the modified nano-silica; 2, uniformly mixing the phenolic resin, the modified nano-silica, the curing agent and the toughening agent at 50-60 DEG C to obtain a mixture A; and 3, mixing and uniformly stirring the mixture A, the surfactant and the foaming agent, rapidly pouring the obtained mixture into a preheated die, foaming the mixture, and curing the mixture to obtain the heat insulation board. The heat insulation board has the advantages of high strength, high oxygen index, good toughness and low heat conduction coefficient.