Two-dimensional model of conjugate heat and mass transport in Chemical Vapour Infiltration (CVI) process was developed. The model was used for simulation of Isothermal CVI production of SiC matrix composite. Flow pattern, thermal field and distributions of species concentrations in the gas region of the reactor and in the porous preform were analysed. Temperature and species concentration distributions were found to be noticeably non-uniform. The non-uniformity of parameter distributions leads to non-uniform densification of the preform both along the preform thickness and height.