We reported on a master-oscillator fiber power amplifier (MOPA) system and a second-harmonic generation (SHG) system. Actively Q-switched Nd:YVO(4) laser was used as a seed source of light pluses. The MOPA system produced as much as 76 kW of peak power at wavelength of 1064 nm, with 35 kHz repetition rate and 20 ns pulse duration. With a lithium triborate (LBO) crystal at type II phase matching, a maximum 16 kW of peak power had been demonstrated. The fiber nonlinear effects such as stimulate Brillouin scattering (SBS) and stimulate Raman scattering (SRS) and the SHG conversion efficiency were investigated.