In this presentation,we report the results of performance testing on a wavelengthscanned cavity ring-down spectroscopy (WS-CRDS) instrument (Picarro Inc.,CA,USA,model G1301) for continuous CO2 and CH4 measurements both in the laboratory and the fields.The performance testing in labs have shown the capability of this analyzer on simultaneous measurements of CO2 and CH4 with reliable accurate measurements and ppbv sensitivity.