The invention relates to an acylation reaction catalyzed by 4-dimethylaminopyridine (DMAP) (the reaction equation is shown in the description). DMAP is dissolved in a non-polar solvent, dry hydrogen chloride gas is injected, and DMAP hydrochloride is obtained through filtration. Under a solvent-free or organic solvent condition, inert alcohol, phenol and amine are reacted with an acylation reagent at 0-130 DEG C in the presence of a catalytic amount of the DMAP hydrochloride; a non-polar solvent is added, and the catalyst of the DMAP hydrochloride can be recovered by filtration. The filtrate is subjected to water washing, alkali washing, liquid separation, organic phase drying, and solvent evaporation to obtain an acylation product. The recovered DMAP hydrochloride can be used in the next catalytic cycle.