Intercell spectrum sharing is a promising technology to improve the spectrum efficiency for 5G networks. However, the co-channel interference caused by spectrum sharing will significantly limit the performance of networks. In this paper, we aim to optimize the power allocation to maximize the system throughput by mitigating the co-channel interference. The power allocation is formulated as a nonconvex optimization problem due to the interference term. To solve the problem, the objective function is transferred as difference of two convex (DC) functions. Then, the later convex function is approximated by the one order Taylor expansion and thus the objective function is transferred as a convex optimization problem. The DC programming method is adopted to solve the problem. Simulation results show that the effectiveness of the proposed power allocation scheme for 5G networks.