The hardware design of a Fourier Transform Infrared (FTIR) analyzer was improved to realize the simultaneous and continuous measurements of greenhouse gases and δ13CO2 values in high Precision. Firstly, the FTIR measurement system was designed and analyzed theoretically, and the temperature and pressure monitoring systems and sealed drying gas circuit were introduced into the spectroscopy. Then the process of quantitative spectral analysis was presented. Finally, the comparative measurements were designed by using standard gases. Experimental results on CH4, CO, CO2 and δ13CO2 indicate that the Standard Deviations(STD) measured by the designed analyzer are 001, 0.011, 0.239×10-6 and 0.572‰, the standard uncertainty of designed measurement system is improved about 6.3, 8.45, 10.54 and 14.73 times that of routine FTIR measurements, and the system errors are improved about 2.88, 1.93, 4.67 and 4.66 times, respectively. The comparison of the measurement results between the analyzer and the Isotope Ratio Mass Spectrometer (IRMS) for δ13CO2 value shows that the STDs are 0.572‰ and 0.171‰ respectively, and the standard uncertainty of the both methods is similar. The FTIR analyzer for greenhouse gases and carbon isotope ratios satisfies the requirements of measurements for multi-species, online and high precision.