The invention discloses a power amplifier digital pre-distortion device and method based on a modified piecewise linear function. The device comprises a digital pre-distorter of a pre-distortion model based on the modified piecewise linear function and a pre-distortion model training module. The digital pre-distorter carries out digital pre-distortion processing to input digital baseband signals; a power amplifier outputs analog baseband signals; after power coupling, orthogonal demodulation and analog-digital conversion are carried out to the analog baseband signals respectively by an attenuation coupler, a broadband orthogonal demodulator and an analog-digital converter, output digital baseband signals are generated; after input digital baseband signals and the output digital baseband signals are synchronized, the signals are input in the pre-distortion model training module; after the pre-distortion model training module carries out parameter training to the signals by using a least squares algorithm, power amplifier model parameters based on the modified piecewise linear function are obtained and are sent to the digital pre-distorter. According to the device and the method provided by the invention, the high order operation in simplifying a Volterra series model is prevented; the digital signal processing difficulty and complexity are reduced; and the complex nonlinear features of the power amplifier can be compensated well.