The present invention discloses a class of isocoumarin derivatives, which have the following general formula, wherein R is selected from hydrogen atom, C1-C10 alkyl, halogen, carbonyl, hydroxyl, nitrile, ester, alkoxy or trifluoromethoxyl, and E1 or E2 is selected from C1-C6 alkyl formate, phenyl or nitrile. The present invention further discloses a synthesis method of the isocoumarin derivatives. According to the present invention, divalent copper is adopted as a catalyst, a simple and easily-available o-halogenated benzoic acid and an alkyne compound are adopted as starting raw materials to synthesize an isocoumarin compound and derivatives thereof, and advantages of low cost, high yield, simple operation, easily-available raw materials, simple reaction equipment, easy industrial production, and the like are provided.