The bromination oxyalkylation of isocoumarin derivatives at 4, 3-position with N-Bromosuccinimide(NBS) or N-chlorosuccinimide(NCS) as bromination reagent or chlorinated reagents, methanol as solvent and raw materials was realized. The addition reaction between 3,4 - sites can take place at room temperature to synthesize isochromanone compounds with potential pharmacological activity. After optimizing the reaction conditions, the results showed that When n(Halogenated agents) : n(Ⅲa)= 2:1, and the alcohol compound was 2 mL, the high yield isocouman-1-ketone derivatives (80%~90%) could be obtained at room temperature (25 ℃) for 7 h.the high yield of isocoumarin 1-ketone derivatives (80%~90%) could be obtained. The structures of the products were determined by 1 HNMR, 13CNMR and HRMS.