Reusing as many existing heat exchangers as possible is one of the most important strategies in retrofitting of heat exchanger networks, which can reduce investment costs and increase heat recovery in the process industry. However, the performance degradation of the existing heat exchangers due to the rough increase or decrease of the heat exchange area during the reuse of the heat exchanger seriously affects the effective implementation of the heat exchanger network retrofit scheme. To fully evaluate the performance of a heat exchanger network, a new methodology for heat exchanger network retrofit is proposed in this work. The performance simulation is introduced into heat exchanger network retrofit model to reassess the performance of reused heat exchange units. The temperature distribution and heat load distribution in the network are corrected. So the performance indicators of the retrofitted network can be accurately evaluated and then the optimal decision can be made. Genetic algorithm is adopted for the optimization of the proposed retrofit problem. Case studies show that the proposed retrofit method can achieve energy saving of 7-59% with a relatively short payback period of investment, and energy recovery of the retrofitted network can reach 59-79%.