In order to achieve the interconnection communications between medium-voltage and low-voltage power line channel, a smart bridge based on channel estimation and equalization algorithm is proposed in the paper. First of all, system components and principle of the bridge are introduced. Then the core algorithm of the bridge is analyzed in detail. In this algorithm, the real-time channel receiving spectrum based on the SIFT fast Fourier transform is estimated firstly. Then according to the slow time-varying characteristics of the channel, the receiving spectrum of the current channel combine with the previous time channel characteristics is used to estimate the current channel equalization value, and constitute a closed-loop feedback link. Experiments show that the bridge system can meet the requirements of the medium-low voltage power line interconnection communication.