The present invention relates to an application of dimethylaminopyridine (DMAP) hydrochloride serving as recyclable catalyst in an acylation reaction (as represented by equation I). The application comprises: dissolving DMAP into a nonpolar solvent, aerating with dry hydrogen chloride gas, and filtrating the solution to obtain DMAP hydrochloride; adding a catalytic amount of DMAP hydrochloride to inert alcohol, phenol and amine under a solvent-free or organic solvent condition, and completely reacting with an acylation reagent at 0-130 ℃; adding a nonpolar solvent, and filtrating the recyclable catalyst, that is, the DMAP hydrochloride; and conducting washing, caustic scrubbing, liquid separation and organic phase drying on the filtrate, and evaporating and removing the solvent to obtain the acylated product. The recycled DMAP hydrochloride can be used in the next catalytic cycle.