In this paper, we study and optimize the energy efficiency performance of heterogeneous network (HetNet) with the help of self-organized network (SON). Firstly, we propose a new and general power model for different types of base stations (BSs), where the impact of system load (including power load and bandwidth load), antenna port, carrier number, as well as the power supply and cooling system, is together taken into consideration. Secondly, we formulate the optimization problem to maximize the overall network energy efficiency, propose to utilize directional antennas in small cell to control the energy distribution, and design a self-organized algorithm to control the antenna pattern, together with the cell association criterion and transmit power level. Finally, we prove that our scheme could achieve considerable performance gain in terms of both energy efficiency and throughput.