Fourier transform infrared(FTIR) spectra of chloroform gas with different concentrations were measured under different resolutions. Combined with data from the environmental protection bureau(EPA) database of America, the chloroform concentrations were obtained under different resolutions with least squares fitting, as well as the coefficients of correlation and the relative errors. The resolution has some influence on its precision. It is very important to choose appropriate resolution to enhance the detection precision of compound.