Abstract: Disclosed is a preparation method for cannflavin compounds. The preparation method has the advantages of cheap and easily available raw materials, few reaction steps, short production period, simple operation, etc. The method comprises: firstly, condensing 4?-hydroxy-3?-methoxyacetophenone and diethyl carbonate (DEC) under an alkaline condition to obtain 4?-hydroxy-3?-methoxybenzoyl acetate; reacting 1,3,5-trihydroxybenzene with bromo-isoamylene under an alkaline condition to obtain 2-isopentenyl-1,3,5-trihydroxybenzene; and finally, condensing 4?-hydroxy-3?-methoxybenzoyl acetate and 2-isopentenyl-1,3,5-trihydroxybenzene at a high temperature to produce cannflavin B and/or isocannflavin B, and then subjecting same to separation and purification to obtain pure cannflavin B and pure isocannflavin B.