A single pulse energy 6.77mJ, repetition rate of 1kHz, pulse width of 11ps at 532nm wavelength with the near top-hat intensity profile in the near filed picosecond laser amplification system is realized using a semiconductor laser side pumped Nd:YAG crystal. The seed pulse is generated in a home-built Nd:YVO4 oscillator, pumped with a 808 nm CW diode laser. The oscillator provides 2.8nJ, 11ps pulse width, 86 MHz repetition rate at 1064 nm wavelength. Pulse from the Nd:YVO4 oscillator is first amplified to 1.5mJ by a diode side-pump Nd:YAG regenerative amplifier. Then the pulse, increased in size by a negative lens, sequentially passed through a circular aperture and a spatial filter-image relaying system to produce a top-hat intensity profile in the modules, and an 8th order super-Gaussian beam is obtained, and total transmission of beam shaping set-up is about 30%. The beam, passed through a double-pass preamplifier of single rod and a double-pass main amplifier of single rod, is amplified up to 17.3mJ, corresponding peak power is 1.57 GW. A 4F relay-imaging system is used in the amplification stages to preserve the top-hat intensity profile and compensate the thermally induced birefringence of Nd:YAG rod. The amplified output beam leaving the double-pass Nd:YAG module is decreased in size and imaged on a 5×5×13 m^3 second-harmonic generation (SHG) crystal-LBO by a 4F relay-imaging system, finally a 532nm approximate top-hat intensity profile in the near filed, which single pulse energy is 6.77mJ, is obtained after doublefrequency. The second-harmonic generation efficiency is over 51%.