A laser diode-pumped picosecond Nd:YVO4 regenerative amplifier system is reported, which produces high stable pulses at 100 kHz repetition rate. RTP crystal is chosen as electro-optical switches to control the output of regenerative amplifier. The amplifier is a symmetrical W type resonator with 1.8 m total length. The effects of round trips number and cavity losses on period doubling bifurcation and maximum output power are analyzed. When pump power is 30 W, the amplifier provides the output power of 5.3 W with pulse stability root mean square (RMS) is less than 2% by choosing the optimal round trips number. The amplified pulse has a pulse duration of 13.78 ps, a peak power of 3.84 MW. The beam quality factor M2 after amplification is less than or equal to 1.5.