Abstract: In order to satisfy the demand of biology, scientific research, industrialization and continuous wave frequency doubling ultraviolet laser, a research on blue diode laser dual end pumped Pr:YLF generating fundamental laser is designed. With the novel method of LD collimating and L-Shaped resonator of thermal lens compensation, a TEM₀₀ red laser radiation at 639 nm with an output power as high as 21.82 W was obtained. To the best of our knowledge, this is the first report on a Pr:YLF laser operating at 639 nm with output power above 20 W. The result of this research satisfies the demand of high output power and the perfect beam quality at the same time.