The survey of dual wavelength crystal lasers is introducted in this paper. Our research results on dual wavelength crystal lasers are described mainly.These are as follow: oscillation condition of a simultaneous multiple wavelength laser has been esta blished and used to analyze the possibility of simultaneous oscillation in various neodymiumhost crystals, such as Nd:YAG, Nd:YLF, Nd:BEL and Nd:YAlO3 (YAP)crystals at transitions from 4F3/2-4I11/2 and 4F3/2-4I13/2.It shown that this kind of laser can be realized in all the described crystals in a pulsed state. In general, continuous wave operation, however, can only be achieved in Nd:YAP crysta1. On the basis of these results. the CW dual wavelength crystal lasing has been achieved for the frist time by using Nd:YAP crystal. The output power of 1079.5 nm and 1341.4 nm was 23.9 W and 25.4 W respe ctively.The Nd:YAG and large energy Nd:YAP dual wavelength pulsed lasers were also acquired. The experimental results show that the temporal and spatial overlops of both beams were quite good for both lasers. In addition.we has obtained 1655 nm and 1663 nm dual wavelength and 27l1 nm, 2730 nm and 2795 nm three wavelength Er:YAP lasers.