The invention discloses a method for synthesizing pyrano-coumarin derivative, comprising: 4-hydroxy coumarin and 1, 3-diaryl-2-allylene-1-alcohol are dissolved in organic solvent to react for 1h at the temperature of 50-80 DEG C under the catalysis of molecular iodine; concentrated sulfuric acid is then added into the reaction product, and the mixed solution is stirred at the temperature of 80-100 DEG C to react for 8-12h; then, saturated sodium sulfite solution is added, ethylacetate is used for extracting, and organic phase anhydrous sodium sulfate is dried and processed by reduced pressureconcentration; finally, after being purified by column chromatography, the pyrano-coumarin derivative can be obtained. The method has mild reaction condition, low cost, simple technique as well as convenient and fast operation.