In this study, the natural convection heat transfer is numerically examined in a square enclosure filled with a non-Newtonia power-law fluid. Two fixed temperature baffles are mounted on the left wall of the enclosure. The left wall of the enclosure and the baffles installed on it, are at a constant temperature of T_h and the right wall of the enclosure is at a constant temperature of T_c, while its horizontal walls are thermally insulated. The governing equations for the power-law fluid flow are solved with the numerical finite difference method based on the control volume formulation and SIMPLE algorithm. The study investigates the effects of relevant parameters such as the Rayleigh number (〖10〗^3≤Ra≤〖10〗^6), the power-law index (0.8≤n≤1.4), the baffles length (0≤B≤0.5) and the baffles distance from each other (0.1≤D≤0.8) on flow and temperature fields and the rate of heat transfer. The results show that an increase in Rayleigh number, particularly when n