An L-band switchable dual-wavelength, frequency stabilized, high energy, single frequency, single mode linearly polarized, pulsed laser based on a master osocillator power amplifier (MOPA) configuration was reported. It could be used as the emission source of detecting atmospheric CO₂ LIDAR system. This pulsed fiber laser system was mainly composed of two single frequency narrow linewidth external cavity semiconductor lasers, pulse modulation system, and multi-stage fiber amplifiers. The wavelengths of 1572.018 nm and 1572.480 nm could be switched freely by controlling a magneto-optical switch. Using the closed loop temperature control technology, the locked central frequency and output optical power were implemented. The on-off extinction ratio of 80 dB was achieved by using digital and analog acousto-optic modulators in series. The Stimulated Brillouin Scattering (SBS) threshold was increased by applying non-uniform stress to the fiber. With a common commercial gain fiber and commercial polarization maintaining components, an average output power of 1.5 W, pulse width of 309 ns, the peak power of 485 W, pulse energy of 150 μJ and signal to noise ratio of 25 dB were generated at a repetition rate of 10 kHz and the wavelength of 1572 nm. The power consumption of the whole laser system which used air cooling was less than 60 W.