High average power linearly- polarized nanosecond- pulsed, modulated diode seeded thuliumdoped fiber laser based on master oscillator power amplifier (MOPA) system is reported. The modulated seed laser delivers 20 ns pulses with tunable repetition rate from 200 kHz to 1 MHz. The MOPA yields 100 W average output power at 200 kHz repetition rate. The pulse duration reduces to 6 ns during amplification due to gain reshaping effect, which lead to a higher peak power of 83 kW with pulse energy of 0.5 mJ. To the best of our knowledge, this is the first demonstration of average output power exceeding 100 W from a linear polarization, thulium doped fiber laser using modulated diode as a seed.