This work achieves a variety of wavelength output modes in the same laser by analyzing the energy level lifetime and thestimulated emission cross section. The laser realizes the result by the regulation of the pump pulse mode without any tuning components in the cavity and does not change the output coupling transmittance.The laser modes include： 1.06 mJ single-wavelength 2 699 nm laser mode， 1.25 mJ single-wavelength 2 803 nm laser mode， alternate sequence pulse mode with dual-wavelength of 1.06 mJ 2 699 nm and 0.86 mJ 2 803 nm， alternate sequence pulse mode withdual wavelength of 1.06 mJ 2 699 nm laser and 1.35 mJ 2 830 nm.The research in this paper is expected to be the laser source of the differential absorption radar for measuring the concentration of organic matter， enabling a single detector to achieve differential measurement， while greatly simplifying the detection system of differential absorption radar and reducing costs.