Deploying heterogeneous networks is a key move to increase the capacity of mobile communication systems. However, the high transmit power of the macrocell base station can cause severe interference to the edge users of the microcell; at the same time, the macrocell users around the microcell base station can also be interfered by the proximity of the microcell base station, so these users should be protected. By studying the resource allocation and power control strategies in the downlink transmission of heterogeneous networks, we propose a resource allocation and power control strategy based on user partitioning. Firstly, the users are classified according to the ratio of signal interference to noise, and a guard band is designed for the edge users with severe interference. In addition, by dynamically adjusting the transmission power of each base station on the guard band, the interference on edge users is mitigated without sacrificing system performance. Simulation results show that compared with the traditional scheme, the proposed strategy can effectively suppress the interference on macrocell and microcell edge users and improve the throughput of the whole system.