The natural convetion of nanofluids in an inclined square cavity are numerically simulated by using Chebyshev collocation spectral methods. The left-hand and right-hand walls of the cavity were kept at a constant temperature, while the upper and lower walls were insulated. The magnetic field parallel to the lower wall of the inclined cavity is imposed. The cavity is filled with different nanoparticles, based on water. The effects of pertinent parameters such as the inclined angle of the square cavity, Grashof number and the solid nanoparticles on the fluid flow and heat transfer of nanofluids. The results show that the heat transfer of nanofluids is maximum when the inclined angle is p/4, while the heat transfer of nanofluids is restrained when the inclined angle is p/3. The fluid flow and heat transfer of nanofluids are a significant change with Grashof number. The influence of different nanoparticles on heat transfer is similar.