In order to study the output characteristics of simultaneous dual-wavelength laser and solve the problem of gain competition,this paper introduces the theoretical model of dual- wavelength laser which can output quasi-three-level laser and a four-level-laser at the same time,and deduces the expression of output power of dual wavelength laser.Based on the theoretical model,a simultaneous dual-wavelength continuous wave′s laser with an intra-cavity cascade pump structure pumped by an 879 nm laser diode was designed for the first time.The quasi-three-level CW laser at 912 nm and the four-level CW laser at 1064 nm have been achieved successfully.At a maximum pump power of 15 W,the 912 nm quasi-three-level laser with a maximum output power of 0.65 W is obtained,with a slope efficiency of about 7 %,and the 1064 nm four-level laser with a maximum output power of 1.58 W,the slope efficiency is about 16.6 %.The total optical to optical conversion efficiency is 14.9 %.In the experiment,it is found that the output power of two wavelengths varies with the spacing between two crystals,and there is a competitive relationship between the two wavelengths.