A process for separating an alkylation product includes introducing a liquid phase alkylation product from an alkylation reaction unit into a first heat-exchanger directly or after being pressurized with a pressure pump and heat-exchanged with a vapor phase stream from the column top of a high-pressure fractionating column, then into a second heat-exchanger and subsequently into the high-pressure fractionating column. The vapor phase stream from the column top of the high-pressure fractionating column is heat-exchanged with the liquid phase alkylation product to be separated, a liquid phase stream from the column bottom of the high-pressure fractionating column is introduced into a low-pressure fractionating column and subjected to fractionation under a condition of 0.2 MPa-1.0 MPa, a low-carbon alkane is obtained from the column top of the low-pressure fractionating column, and a liquid phase stream obtained from the column bottom of the low-pressure fractionating column is an alkylation oil product.