Abstract: An all fiber,compact high power tunable laser source for atmospheric CO2 measurement was investigated.Based on the ultra precise atmospheric CO2 absorption spectrum,a tunable seed laser was designed with the peak absorption around 1572nm,and then its output power was amplified to the order of watt level with an Er-Yb double cladding fiber amplifier.The experimental results show that the laser can provide 10dBm output power with 50dB side mode suppression,500kHz linewidth;the max gain of the fiber amplifier is 25.13dB,output power is 1W.This laser possesses a small size,low power consumption and low cost it builds a steady foundation for the wider range of Atmospheric CO2 measurements.