The invention provides a method for re-crystallizing a key intermediate of a hepatitis C virus drug velpatasvir. Highly pure 9-bromo-3-(2-bromoacetyl)-10,11-dihydro-5H-benzo[D]naphtho[2,3-B]pyran-8(9H)-one is obtained, and parts of organic solvents can be recovered, so the method is economical and environmentally friendly. The method concretely includes the following steps: dissolving crude 9-bromo-3-(2-bromoacetyl)-10,11-dihydro-5H-benzo[D]naphtho[2,3-B]pyran-8(9H)-one in a mixed solvent containing a high-solubility organic solvent A and a low-solubility organic solvent B under a 35-70 DEG Cheating condition, precipitating crystals by a gradient cooling technology, centrifuging the obtained system, carrying out vacuum drying on the obtained wet solid at 30-70 DEG C, and performing normalpressure distillation on the obtained centrifugal mother liquor to recover the solvent B.