In this study, a numerical simulation is performed to study natural convection of water based nanofluid in an inclined square side wavy walls cavity. The the top and bottom walls of the cavity are assumed to be adiabatic and the side walls are at different constant temperatures. Three different nanoparticles, Cu, CuO and Al2O3 are used in the study. The computations are conducted for solid volume fractions of 0%, 5% and 10% and for Rayleigh number of 10(4), 10(5) and 10(6). The analyses were conducted for 0 degrees, 45 degrees and 90 degrees inclination angle for enclosed cavity, 0.05, 0.075, and 0.1 amplitude and 1 and 3 undulation numbers. The results show that heat transfer rate increases with the increase in nanoparticle volume fraction and Rayleigh number. Additionally, it is observed that increasing undulation number increases heat transfer rate significantly.