We have studied the frequency doubling and triple doubling of high-power and high-repetition frequency picosecond lasers. We selected a 1 030 nm Yb-doped fiber laser with a power of 50 W, a repetition frequency of 50 MHz, and a pulse width of 10 ps as the pump source. LBO crystal is used as frequency doubling crystal, the length of the crystal is 20 mm and the beam spot radius is 0.03 mm when the class Ⅰ angle phase matching is obtained through simulation, and the frequency doubling conversion efficiency is 28.08%; the temperature phase matching of the class I is obtained, the crystal length is 20 mm and the spot radius It is 0.039 mm, and the frequency-doubled conversion efficiency is 76.4%. LBO crystal is selected as the triple frequency crystal, and the relationship between triple frequency efficiency and crystal length and spot radius is explored through the type II angle phase matching method. Finally, the energy ratio of the fundamental frequency light to the frequency doubled light is 2∶3, and the crystal length is 20 mm. The spot radius is 0.05mm, and the theoretical conversion efficiency is 18.67%.