Picosecond pulse fiber laser oscillator with narrow linewidth and multistage fiber amplifier which are used in the fiber-solid picosecond laser source are optimally designed. Spontaneous emission and nonlinear effect in the fiber are fully suppressed by fiber link, so that when the system operates at 1 kHz repetition rate, the spectral signal to noise ratio is still better than 20 dB and the spectral bandwidth is narrower than 0.5 nm. Furthermore, picosecond pulse generated from the fiber link is further amplified by a three-stage double-pass Nd∶YVO4 solid amplifier. The average output powers of the laser system are as high as 2.34, 4.30, 10.30 W, corresponding to 2.34, 0.43, 0.10 mJ single pulse energies at 1, 10, 100 kHz repetition rates. With only passively cooling on the Nd∶YVO4 crystals, beam quality M2 is less than 1.3 and beam roundness is more than 90% when the output power of system doesn′t exceed 7 W.