The invention discloses a double-frequency power amplifier digital predistortion device and method based on a piecewise linear function, which comprises a first digital pre-distorter, a second digitalpre-distorter, a first digital-to-analog converter, a second digital-to-analog converter, a first low-pass filter, a second low-pass filter, a first modulator, a second modulator, a first power divider, a power amplifier, an attenuation coupler, a second power divider, a first band-pass filter, a second band-pass filter, a first demodulator, a second demodulator, a third band-pass filter, a fourth band-pass filter, a first analog-to-digital converter, a second analog-to-digital converter and a predistortion training module. The invention also discloses a double-frequency power amplifier digital predistortion method based on the piecewise linear function. The device and the method in the invention reduce the number of parameters in the existing 2D-DPD double-frequency power amplifier predistortion model, thereby reducing the implementation difficulty and consumed computing resource of a model in the FPGA and accelerating the computing time of the optimal model parameter.