Abstract: The frequent environmental events about the polluted gases ask for some kinds of multi-gases analyzer. Limited to the general aim of design and incomplete function in software, the conventional Fourier Transform Infrared spectrometer can't be effectively involved in the field of gases analysis. To solve this problem, a new method was studied using the magnetic encoded signal to drive the moving cube and collect the spectrum data, instead of the conventional laser interference signal. It was in this way that a concise structure of analyzer was established and it facilitated the procedure of debugging and setting-up. At the same time, in order to meet the demands of continuous and immediate analysis, an improved quantitative algorithm with the ability of baseline compensation automatically was illustrated. The related experiments with the designed gases analyzer which is verified to be an effective tool for environmental gases monitoring can execute the multi-gases quantitative analysis rapidly and continuously.