This paper is aimed at 3-dimensional measurements of temperature and concentration with multi-layers for CT-TDLAS(Computed Tomography Tunable Diode Laser Spectroscopy). The calculation results with the measurement system for the distributions of temperature and concentration of the exhaust gas field showed clear differences of temperature and concentration fields at each layer. In this paper, the H2O vapor was considered as target gas for measurements, and the wavelength range of the diode laser was set at 1388.0 ~ 1388.6nm where the absorption occurs. Double layers were installed with height difference of 15mm, and 16 lines (8×8 path) were constructed at each layer. Additionally, new curve fitting method(exponential and weighted curve fitting) and reconstruction algorithm(SMART method) was adopted to enhance the performances of CT-TDLAS. To estimate the performances of the constructed CT-TDLAS, the temperatures calculated by the CT-TDLAS were compared with those measured by the thermocouples. It has been verified that the relative error range is 0~33%.