A high power linearly polarized Yb fiber laser with picosecond pulse bunch output was designed based on the seed consisting of a gain-switched distributed Bragg reflectorstructured laser diode, which emitted the picosecond pulses with a pulse duration of 200 ps and a repetition rate of 350 MHz. During pre-amplifying, a first-order diffraction transimission acousto-optic modulatorwas used to generate the picosecond pulse bunches, and the repetition rate of the bunches was tunable from 10 kHz to 500 kHz. The picosecond pulse bunch laser was power-amplified using a large mode area polarization maintaining Yb-doped fiber. A high power linearly polarized laser was obtained with an average power of 83 W, a peak power of 12 kW, and an extinction ratio of better than 15 dB. The peak power of 12 kW was obtained under the 100 kHz repetition rate of the pulse bunch, which was composed of 350 sub-pulses. Compared with the conventional continuous wave pulsed lasers, the pulse bunches were able to be obtained by this system, which benefited the further increase of the peak power. This system can be applied to the area of laser micro-machining.