The invention provides a preparation method of a high performance modified phenolic resin refrigeration house insulation board. The preparation method comprises following steps: step one, dissolving phenolic resin into ethanol under a heating condition, adding melamine cyanurate, nepeta oil, and dodecyl ethyoxyl sulfobetaine, stirring, mixing, cooling, sequentially adding sodium citrate, calendulaextract, and nano diatomite, stirring, mixing, extruding, and cutting to obtain modified phenolic resin; step two, weighing raw materials; step three, evenly mixing modified phenolic resin and sericite powder at a high speed, adding a hydrocarbon composition, sodium dioctyl sulfosuccinate, and a foaming agent, and stirring to obtain a mixture (A); and step four, adding a curing agent into the mixture (A), stirring, transferring the mixture (A) to a mould, foaming, moulding, and demoulding to obtain the insulation board. The preparation method has the advantages of simple operation and good raw material compatibility. The prepared insulation board has the advantages of good fire resistant property, excellent waterproof property, good anti-aging performance, and low heat conductivity coefficient, and has a long service life in a damp environment.