A high-power picosecond mode-locked Nd∶YVO4 laser system with high repetition-rate of 80 MHz is reported. When the pump power is 22.4 W, the oscillator provides the output power of 5.1 W with signal-tonoise ratio more than 60 dB and a pulse duration of 23.7 ps. The semiconductor saturable- absorber mirror (SESAM) of oscillator can work for more than 500 h without any damage by selecting reasonable SESAM parameters and suitable cavity. The power is amplified to 44 W by two stages of power amplifier end-pumped by a continuous- wave 888 nm laser diode (LD). Optical- optical conversion efficiency of amplified system is more than 25%. The beam quality factor M2 after amplification is less than 1.5.