This work presents a retrofitting approach for heat exchanger networks (HENs) for single-period and multiple-period operations, aiming at the improvement of operation flexibility of HENs. A two-step method is proposed to solve the problems of redundant heat transfer areas in multiperiod HENs and the incomplete utilization of existing heat-transfer areas in HEN retrofit. In this approach, a multiperiod HEN design model is first solved to target the retrofit. Then, the final HEN is obtained by matching the required heat exchangers with the existing ones in reverse order. The proposed matching procedure is provided in detail and mathematically proven. Three case studies are employed to illustrate the advantages of the proposed method for solving the problems in the multiperiod HEN retrofit. In addition, the proposed method is extended to solving single-period HEN retrofit problems. Results indicate that the proposed method makes full use of the existing heat exchangers to reduce retrofit costs and increases the energy utilization efficiency of the HEN in multiperiod operations. The proposed method is simple and easy to implement. It can reduce the computational load and the difficulties in solving practical industrial problems.