Among different types of power supplies for transformer calibration, the common electric power supply does not have precise adjustment, the switching type inverter power supply is easy to produce harmonic interference, and the efficiency of linear power supply is relatively low. To solve these problems, this paper develops a high efficiency linear power amplifier scheme based on piecewise linearization, which can effectively improve the output waveform quality of power supply, improve the overall efficiency of power supply, greatly reduce the heat loss, and realize the fine regulation of output voltage. The proposed circuit topology has the characteristics of multi-level hierarchical structure. The sinusoidal signal is linearized by segments, which greatly reduces the voltage sag of the power transistor in operation. Therefore, the system efficiency is greatly improved, while the advantages of the traditional linear power amplifier, such as high output waveform quality and low electromagnetic interference, are retained. An eight-level power amplifier is built to verify the correctness of the scheme, and it turns out that the highest efficiency reaches 94%, showing good performance.