Based on the influence of nonuniform temperature distribution on interconnect delay, an analytical model to estimate the optimal size of repeaters inserting RC interconnect is presented in this paper. In the proposed analytical model the temperature distribution is taken into account and a temperature correction factor is introduced to modify the repeater size and obtain the optimal interconnect delay. Adopting parameters of 90 nm and 65 nm process technology, the proposed model is compared with the model without considering the temperature distribution. Results show that the new model is more accurate and saves the repeater insertion area with maximum values of 15.6% and 36.7% in 90 nm and 65 nm technology, respectively.