A reliable bus type switching method based on holomorphic embedding is proposed to address the non-operational solution issues that may arise from bus type switching in power flow calculations. Firstly, a power flow equation considering the reactive power and voltage constraints of generator buses is constructed, and the non-operational solution problems that may arise from commonly used bus type switching methods are analyzed. Then the holomorphic embedding form of power flow equation is designed based on complex analysis theory and holomorphic embedding method. The recursive equations of voltage and generator reactive power series are derived. Based on the power series of generator reactive power, the sequence of generator reactive power of limit is judged and the framework of bus type switching is designed. Finally, IEEE standard calculation examples are tested to indicate that the proposed method can reliably obtain operational solutions for power flow equations.