Abstract: Power flow (PF) calculation plays a critical role in active distribution network (ADN) planning and operation. The existing Newton Raphson (NR) and forward backward substitution (FBS) methods can solve the PF of ADN, but they may fail in convergence and computational efficiency. The holomorphic embedding method (HEM), as a novel PF method, can effectively avoid the above problems, but the existing HEM does not fully consider the different types of distributed generation (DG), the diversity of the control modes of soft open point (SOP), or the voltage and frequency characteristics of the loads. This poses a challenge in resolving PF of ADN under different operating modes. Aiming at the above problems, this paper firstly proposes a unified HEM for ADN, which can solve PF of ADN including multiple types of DG, SOP and operating in grid-connected or islanded mode. Next, according to the static voltage and frequency characteristics of the load, HE PF models of the loads are constructed. Then, according to different grid connection methods of DG and the different operation modes of ADN, DG is equivalent to different types of buses, and HE PF models of various DG are formed. Further, considering the different control modes of SOP, HE PF models of SOP are formulated. According to the principle that the same power coefficient is equal, the holomorphic functions are solved to get the recursive relationship, which is used to solve each power coefficient. Meanwhile, the approximation values of voltage, frequency and reactive power are obtained by using the analytical continuation to realize the accurate PF solution of ADN. Finally, the accuracy and effectiveness of the proposed method are validated by using the modified IEEE 33-bus and IEEE 123-bus test systems.