The strong scattering of light transported through nanoporous ceramic media can be used to form a miniature gas sensing absorption chamber by adopting the tunable diode laser absorption spectroscopy (TDLAS). To explore the effect of the physical parameters of ceramics on the optical pathlength enhancement, TDLAS was utilized to measure the spectral absorption characteristics of oxygen inside the ceramics and to study the effect of the thickness and porosity of ceramics on the pathlength enhancement coefficient. The experimental results show that the pathlength enhancement coefficient is linearly correlated to thickness and exponentially correlated to porosity, which provides experimental explanation for the pathlength enhancement mechanism. In conclusion, the physical parameters of ceramics can be optimized to improve the pathlength enhancement coefficient and form a miniature gas cell suitable for in-situ TDLAS applications.